pressure relie

© 2009 Fluor. All Rights Reserved.

Pressure Relief/Safety Valve 101

Gobind Khiani, P.Eng

DISCLAIMER

- The content of this presentation are intended for educational purposes only and do not replace independent professional judgment. They do not constitute advice and should not be relied upon in making or refraining from making) any decision.

- Statement of fact and opinions expressed are those of the speaker alone and are not the opinion or position of his employers, past or present, nor those of the professional bodies and committees in which he participates.


To establish baseline

framework using existing

ELM(Energy Lean

Management Systems- Part 1)

and the Spec’s.


Energy Lean

Management

Systems – Part 1

Pressure Safety Valve Vs Safety Relief Valve

Pressure Safety Valve(PSV) ISA Symbol

♦ Valve which is designed to relieve excess pressure. Designed to be snap-acting open/closed.

Pressure Relief Valve(PRV, Upstream pressure)

(PCV, Downstream pressure)

♦ A valve which opens in throttling action or in proportion to the increase in pressure over the

opening pressure. Essentially a regulator.

Safety Relief Valve(SRV) Not used in ISA Symbology

An automatic pressure relieving device. This is

similar to a Pressure Safety Valve.

ELM Common Terms used in Pressure

Relief/Safety Valves

♦ Set Pressure: The inlet pressure at which the PSV or

PRV is adjusted to open under service conditions.

♦ Actual Orifice Area (ASME Area): The measured

minimum net area which determines the flow through a

valve.(applies only to PSV)

♦ Coefficient of Discharge: The ratio of the measured

relieving capacity to the theoretical relieving capacity.

MAWP: The maximum gauge pressure allowable at the

top of a completed vessel in its normal operating position.

ELM Common Terms used in Pressure

Relief/Safety Valves

Accumulation: The pressure increase over the MAWP

of the vessel during discharge.

Overpressure: The pressure increase over the set

pressure of a PRV.

♦ Relieving pressure: The sum of the set pressure and

over pressure.

♦ Blowdown: The difference between the set pressure

and the closing pressure of a PSV.

ELM Common Terms………..Contd.2

♦ Back pressure is the pressure that exists at the outlet of a

pressure relief device as a result of the pressure in the

discharge system. It can be broken down as follows:

♦ Constant

♦ Superimposed

♦ Built-up

♦ Variable

♦ Effects due to back pressure may include variations in

opening pressure, reduction in flow capacity, instability, or a

combination of all three.

ELM Common Terms…….….Contd 3

♦ Design Pressure: Design Pressure is equal to or less than Maximum Allowable Working Pressure (MAWP). MAWP is the maximum gauge pressure at the top of the vessel. Set Pressure should not be more than 90% of the MAWP.

♦ Test Pressure: Cold Differential Test Pressure is the pressure at which the PSV/SRV is set to open on the stand with corrections for service conditions; for example, Temperature and Constant Back Pressure.

♦ Set Pressure: The inlet gauge (static) pressure at which the PSV is set to open. This pressure can be defined differently by each manufacturer but has to be shown in the National Board's 'Red Book.' For example, definition of Set Pressure for Air, Gas, or Steam is 'initial audible discharge' (not 'pop').

Energy Management Criticality

Energy Management Characteristics of

Pressure Relief/Safety Valves

♦ These Valves are designed to:

1. Open and relieve excessive pressure in piping systems.

2. They close automatically after fail below set pressure

(normal pressures are restored) by system design.

3. These valves function or act when normal operating

controls fail to act.

NOTE: These valves are :

- Not designed to control the normal operating pressure.

- Most critical valve in a pressurised piping system.

- These are commonly known as Pressure Relief/Safety

Valves(PRSV)

ELM Purpose of Pressure Relief/Safety Valves

♦ Protection of:

- Personnel, plant, property, production.

♦ Used towards Compliance of:

- Regulatory requirements, Insurance, Safety and

Codes.

ELM Specifications on Pressure Relief Valves

♦ 1.0 Introduction

♦ 2.0 References

♦ 3.0 Life Cycle

♦ 3.1 Design

♦ 3.2 Installation

♦ 3.3 Operation

♦ 3.4 Maintenance / Servicing

♦ 3.5 Reset / Replace

♦ 4.0 Responsibilities

♦ 4.1 Engineering

♦ 4.1.1 The Project Engineers Responsibilities

♦ 4.1.2 The Facility Engineers Responsibilities

FORM


♦ 4.2 Inspection

♦ 4.2.1 The QA Site Leads Responsibilities

♦ 4.2.2 The Facility Integrity Coordinators Responsibilities

♦ 4.3 Operations & Maintenance

♦ 4.3.1 The Chief Engineer’s Responsibilities

♦ 4.3.2 Operations and Maintenance Personnel's

Responsibilities

♦ 4.4 PRD Service Company


♦ 5.0 Transportation Requirements.

♦ 6.0 Forms

♦ 7.0 Record Keeping Systems

♦ 8.0 PRESSURE RELIEF VALVE REPLACEMENT and

RESET AUTHORIZATION FORM

♦ 9.0 PSV TURNAROUND INFORMATION DATA FOR

♦ PRD AUDIT FORM – Static Data Verification

♦ PRD AUDIT FORM – Visual Inspection Installation Checklist

♦ 10.0 PRD SERVICE DEFERRAL REQUEST FORM


Types of Pressure Relief

Valves

Types of Pressure Relief/Safety Valves

♦Relief Valve used in liquid

service.

♦Safety Valve used in

vapor/gas service.

♦Safety relief valve – liquid or

vapor/gas service.

Relief Valve in Liquid Service

♦ These valves are:

- Operated by static inlet pressure.

- Opens in proportion to the

Pressure over the system opening

pressure.

Safety Valves in vapor/gas service

• These valves are:

-Automatically actuated by

static inlet pressure.

-Characterized by rapid pop

action or opening.

-Typically has exposed or

open spring area.

-Process media goes

via/through valve.

Pressure Safety Valves-Liquid or vapor/gas

service

These valves are:

• Opening mechanism type.

- Quick opening or pop

opening.

- Proportional.

• Two designs

- Conventional

- Balanced


♦ Types of Designs:

-Direct Spring loaded valve.


♦ Spring Loaded PSVs are designed as:

- Spring force holds disc closed by pressing disc

against the nozzle.

- Downward force maintains seat seal.

- When force of flow from below increases to a

pressure greater than that of spring above, the disc

lifts.


♦ Spring loaded PSV operation:

- Closed position:

- The spring force higher

Than upward system pressure

On disc.


Spring loaded PSV

operation

Open Position:

Spring force is

reduced due to

force from inlet

flowing pressure on

disc.

Pressure Relief/Safety valve 101

♦ Huddling Chamber is useful:

- Assist in full-lift of valve.

- At a set point, increases the

Pressure area exposed to.

- Uses direction change of

Flowing process to obtain

Lift.


♦ The earlier slides from 20-27 discussed the

Conventional direct spring loaded PSVs

Basically these PSVs are:

- Spring housing vented to discharge at side of valve.

- Operational characteristics are:

Opening and closing pressure, relieving design and

capacity.

♦ Operational characteristics directly affected by

changes in “back pressure in outlet of valve.”

Pressure Relief/Safety Valves 101

♦ Now we will discuss

-Balanced direct spring-loaded PSVs

The design of these incorporate

Means of minimizing effect of

Back pressure on operational

Characteristics of valve

By using bellows.

Pressure Relief/Safety Valve 101 – Pilot

Valve

♦ Pilot Valves


♦ Pilot Control Benefits:

– Robust and insensitive to vibration –

safe operation also in case of vibration

and oscillation in the plant

– Wide pressure range from

2,5 – 102 bar / 36 – 1480 psig ensures

the applicability for a variety of application

fields

– Simple material change as all pilot parts

are lathe formed. So also parts of custom material

can easily be produced

– Back flow preventer integrated into manifold

block to improve the the variable use of the standard design


♦ Pilot Operated Valve Benefits:

Integrated control lines of the pilot in the cover. Reduction of

the danger of leakage points, pipeline damages and

freezing of condensate.

Integrated brackets at the body for an

easier handling and a safe assembly.

Self draining body angle type avoids

residues and reduces corrosion

Soft seal discs meet the increased

Requirements of the functional tightness

All process-wetted parts in tubing and pilot valve are either

…..stainless steel or nickel-coated


♦ Options available on Pilot operated valve are:

-Back flow preventer.

-Remote Sensing.

-Field test connector.

-Pilot supply filter.

-Manual blow down.

-etc


♦ Pilot operated PSVs

Closing action:

-Pilot control valve diverts

System pressure to the

Main valve.

- Piston force downward

Becomes less than

Seat area upwards.


♦ Pilot operated PSVs

Opening :

-Once the valve senses

Inlet pressure has

Reached set pr.

-Closes inlet pr., sensing

Line, dome.

-Opens vent line, allowing

Dome pressure out.

-Allows pressure under disc

To push up, opening main valve.


♦ Pilot Operated PSVs Principal of Operation:

♦ Reseat action of pilot valve by:

-Senses inlet pressure decreased to closing pressure.

-Closes vent line.

-Allows pressure from sensing line to fill dome.

- Forces disc down onto seat.


♦ Vacuum direct spring loaded PVSV(ISA Symbol)

-These PSVs admits fluid to

Prevent an excessive internal

Vacuum.

- Re-closes to prevent

Further fluid flow after normal

Conditions are restored.


♦ These images are for a Temperature direct spring

loaded PSVs


♦ Rupture Pin Relieve Valve operates as:

♦ Pin Buckles at 3points.

♦ Buckling force > Valve seal friction.

♦ Full open at set point.

♦ The operation is simple as the pin bows the piston

moves up just enough to remove seal stiction.

However the pin is within the elastic limit and the

piston remains on seat.


Rupture Discs


♦Codes, Regulations and Standards Authorities are:

- ABSA

- API

- ASME

- NBB-PVs

- Absa Safety Valve Guidelines……AB524, AB525,

AB506 & AB516


♦ “There is one thing we know for sure about a plan:

“As soon as we finish planning,

the plan is going to change”

♦ Management of Change is not about preventing

change – it is about Managing the Change.


Pressure Safety Valves!!!!!!

♦Why……………….………………………….

♦What………………………………………….

♦How………………………………………......

♦When………………………………………....

♦Where……………………………..........


- Pressure Safety Valve.

- Relief Valve.

- Safety Valve.

- Safety Relief Valve

- Conventional, spring loaded.

Bellow valve.

- Pilot operated valve.

- POV with Reverse flow

preventer.

- POV with Auxiliary filter and

field test Capabilities.

- POV with pilot discharge

tubed to main Valve outlet.


♦ ASME/ANSI B16.5 Pipe Flanges and Flanged Fittings

♦ ASME/ANSI B16.34 Valves Flanged Threaded,& Welded End

♦ ASME/ANSI PTC 25 Performance Test Code

♦ ASME PTC 25 Pressure Relief Devices Performance Test Codes

♦ National Board of Boilers and Pressure Vessel Inspectors Code.

♦ API 520 Sizing, Selection, and Installation of Pressure-Relieving

Devices in Refineries.

♦ APIRP 521 Guide for Pressure Relieving and Depressurizing

Systems.

♦ API 526 Flanged Steel Pressure Relief Valves.

♦ API 527 Seat Tightness of Pressure Relief Valves.

♦ API 576, 580 & 581 Risk Based Inspection


♦ AD 2000 Venting Atmospheric & low Pressure Storage Tanks .

♦ ISO 4126 - Part 1 Safety devices for protection against

excessive pressure, Part 1: Safety Valves


excessive pressure, Pilot operated safety valves.


excessive pressure, Application and installation of safety

devices excluding standalone bursting disc safety devices.

♦ Pressure Vessel Relief Committee,

♦ IPEIA

♦ NACE

♦ ABSA, AB506, 516, 524 & 525


American Society of Mechanical Engineers

The Committee's function is to establish rules of

safety governing the design, the fabrication and

the inspection during construction of boilers and

unfired pressure vessels, and to interpret these

rules when questions arise regarding their intent.

The objective of the rules is to afford reasonably

certain protection of life and property and to

provide a margin for deterioration in service so as

to give a reasonably long safe period of

usefulness


♦ASME CODE, SECTION I, Fired Vessels,

Code Stamp V

♦ This is a construction code covering power, electric

and miniature boilers and high temperature boilers

used in stationary service. This section includes

power boilers used in locomotive, portable and

traction service. Above 15 PSIG.


ASME Section I, Performance Requirements

– 3% maximum overpressure at rated capacity.

– 6% maximum blow down.

– Set pressure tolerance:

• +/- 2 psi Pset>70 psig

• +/- 3 psi 71 psi<Pset<300 psi

• +/- 10 psi 301 psi<Pset<1000 psi

• +/- 1% Pset>1000 psi

– Must c/w lifting lever.

– Must c/w data plate showing rated capacity in lb/hr steam.


ASME CODE, SECTION III, Nuclear

Vessels, Code Stamp NV

♦ This section covers the design, fabrication and

installation of equipment and vessels for use in

nuclear facilities.


ASME CODE, SECTION IV, Heating

Boilers, Code Stamp HV

♦ This code covers the design, fabrication, installation

and inspection of steam heating, hot water heating

and hot water supply boilers which are directly fired

by oil, gas, electricity or coal.


ASME CODE, SECTION VIII Pressure Vessels, Code Stamp UV

♦ Basic rules for the construction, design, fabrication,

inspection and certification of pressure vessels.

These rules have been formulated on the basis of

design principles and construction practices

applicable to vessels. Stamping and coding are also

covered in this section.


ASME Section 8, Performance Requirements • Maximum overpressure at rated capacity:

– 10% (or 3 psi) - single valve

– 16% (or 4 psi) - multiple valves with at least one set at or lower

than MAWP

– 21% - overpressure due to fire.

• No mandatory blowdown, however, adjustable blowdown

valves must meet 7% test during certification. Recommend

keeping operating pressure < 90% of Pset.

• Set pressure tolerance:

– +/- 2 psi Pset<70 psi

– +/- 3% Pset>70 psi

• Lifting lever required for water >140F, air or steam service.

• Must c/w dataplate showing rated capacity in SCFM air,

USGPM water or lb/hr steam


NATIONAL BOARD OF BOILERS

& PRESSURE VESSEL INSPECTORS

♦ The N.B. represents the enforcement agencies who

assure adherence to provisions of the ASME boiler

and pressure vessel code. Its members are the chief

inspectors or other jurisdictional authorities who

administer the boiler and pressure vessel safety laws

in the united states and Canada.


NATIONAL BOARD OF BOILERS

& PRESSURE VESSEL INSPECTORS

♦ Sets Inspection Standards

♦ Qualifies Inspectors

♦ Works for Owners, Insurers

♦ Maintains Records (“Red Book”)

♦ Looks into Violations

♦ Covers Repair


ASME/NB Certification Program

♦ Valve Capacity Certification (Once when valve is released) To establish coefficient of discharge = K

♦ Manufacturer/Assembler Certification (Once every five years) To review facilities and QC procedures To test two production valves for performance & capacity


♦ API RP520 Part I- Sizing & Selection

Part II-Installation

♦ API RP521 Guide for Pressure-Relieving &

Depressurizing Systems

♦ API Std.526 Flanged Steel Safety Relief Valves

♦ API Std.527 Seat Tightness of Pressure Relief

Valves

♦ API Std.2000 Venting Atmospheric & low Pressure

Storage Tanks

♦ API576, 580 & 581 Risk Based Inspection


API 520 Part 1, Sizing and Selection

♦ The information in this recommended practice is

intended to supplement the information contained in

Section VIII of the ASME Boiler and Pressure Vessel

Code. It contains…

♦ Terminology

♦ Pressure - Level Relationships

♦ Causes of Overpressure

♦ Basis of Relief Capacities selected conditions


API 520 Part 2, Installation

The information in this recommended practice is intended to cover methods of installation for pressure relief devices for equipment that has an MAWP or 15 psig or greater. It contains…

♦ Inlet Piping to PRD’s

♦ Discharge Piping from PRD’s

♦ Isolation Valves

♦ Bonnet / Pilot Vent Piping

♦ Drain Piping

♦ PRD Location (Pressure Drop etc)

♦ Multiple PRV’s staggered settings


API 521, Guide for Pressure Relieving and

Depressurizing Systems

♦ Developed as a guide for plant engineers in the

design, installation, and operation of pressure-

relieving and depressuring systems. It also

recommends economically sound and safe practices

for pressure relief. It contains…

♦ Causes of Overpressure

♦ Determination of Individual Relieving Rates

♦ Selection of Disposal Systems

♦ Disposal Systems


API 526, Flanged Steel Pressure Relief Valves

♦ This standard is a purchase specification for flanged

steel pressure relief valves including direct spring

loaded pressure relief valves and pilot operated relief

valves. It contains…

♦ Design

♦ Material

♦ Inspection and Shop Tests

♦ Identification and Preparation for Shipment


API 526 has standardized the following items:

Orifice designation and area(D to T)

Valve size and pressure rating,

inlet and outlet

Materials

Pressure-temperature limits

Center-to-face dimensions, inlet and outlet

Sizing independently from manufacturer

Inspection and shop tests

Identification and preparation for shipment

Flanged safety valves only


API 527, Seat Tightness of Pressure Relief Valves

♦ This standard describes tests to determine the seat

tightness of metal and soft-seated pressure relief

valves. Valves of conventional, bellows, and pilot-

operated designs are covered. Acceptable leakage

rates are defined. It contains…

♦ Testing With Air

♦ Testing With Steam

♦ Testing With Water

♦ Testing With Air – Another Method


NACE

♦ There are different NACE specifications that can be

met when selecting PSV’s

♦ - NACE MR 0175 (2002)

♦ - NACE MR 0175 /ISO 15156 (2003)

♦ - NACE MR 0103

♦ Basic difference between these standards is hardness

testing of parts newer standards requires hardness

testing of pressure containing parts.


Absa

Absa the pressure equipment safety authority, is authorized by the Alberta Government for the administration and delivery of safety programs related to boilers, pressure vessels and pressure piping systems in Alberta. These safety programs are provided to ensure public safety and include the complete life cycle of boilers, pressure vessels and pressure piping systems. The Safety Codes Act allows an ABSA Safety Codes Officer to inspect a boiler or pressure vessel. ABSA is also responsible for the certification of pressure welders, inspectors and power engineers for the operation of a power or heating boiler.


♦ Absa Guidelines on:

Operation, Inspection,

Handling and Servicing of

Pressure Relief Valves


Absa currently adheres on Pressure Relief Valves by

following guidelines and regulations are:

♦ AB 506 and 524.

♦ ASME PTC-25

♦ ASME Section I,IV, VIII, CSA B51 code.

♦ ASME B31.1, NFPA-58 & 59, ANSI K61.1/CGA G-21

♦ API520 Part I and II

♦ NB-23 and NB-18

♦ AB506, API576, 580 & 581

Absa, AB-506

♦ The AB 506 and the following documents have been

issued by the Administrator to define the

requirements that must be met for in-service pressure

equipment under the PESR. When sections of the

recognized industry standards such as the NBIC and

API Codes are referenced in documents issued by

the Administrator, the requirements in these sections

must be met.

Absa, AB-506……...Contd.2

15.0 INSPECTION AND PRESSURE RELIEF VALVE

SERVICING DATE DEFERRAL AND REVISION

♦ Table 1, shows the maximum time that may be

allowed to elapse between thorough inspections and

PRV servicing intervals. Equipment shall be

inspected/serviced by this interval date, unless the

interval has been deferred or revised in accordance

with Section 15.0.

♦ Owner-users must maintain documented procedures

to control and document deferrals and revisions.


♦ 17.0 PRESSURE RELIEF DEVICES

♦ PESR Section 38(1) requires owners to ensure that all

equipment in the pressure system has suitable

overpressure protection to ensure that its authorized

maximum allowable working pressure is not exceeded.

♦ The owner must ensure that all pressure-relief

devices, and the instrumentation and controls that are

necessary to ensure the safe operation of the pressure

equipment, are periodically examined, tested, and

maintained by competent persons in accordance with


♦ documented work processes.

♦ API RP-576 and NBIC Part 2 covers information

regarding the inspection and servicing of

pressure-relief devices. The applicable

information in these documents should be used

to ensure that the pressure-relief devices are

inspected maintained and serviced in

accordance with this section.

Absa, AB-506……..….Contd.5

♦ 17.1 Isolation Valves ♦ The Administrator may accept the installation of block

valves in pressure relief piping for pressure vessels if the

owner meets the requirements of ASME Section VIII,

Division 1 and Appendix M, and submits the relevant design

and rationale to ABSA.

♦ The owner must have an auditable management system

that establishes procedures and training requirements for

the control of such valves. This management system must

be available for review by ABSA at all sites where block

valves are installed in the pressure-relief path.

♦ .

ABSA, AB-506…………Contd.6

♦ A typical management system would include the

following:

-A description of where block valves would be installed;

-The personnel responsible for the system;

-How the valves would be locked or sealed in the proper

position;

-How the valves would be periodically checked;

-Pressure Equipment Inspection & Servicing

requirements AB-506, 2009-05-29 Revision: 6 Page 26

of 34.The procedure required for isolation or servicing of

the pressure-relief device; and the associated training

requirements of all people who work with the pressure

equipment involved.

Absa, AB506……..….Contd.7

♦ 17.2 Maintenance of Pressure Relief Devices

♦ PESR Section 39 states:

-adjustable parts of a pressure-relief device must be sealed at

the time of servicing and remain sealed during operation;

-seals must be installed in a manner that prevents changing the

adjustment of a pressure-relief device without breaking the seal;

-a pressure-relief device must be serviced at an interval

acceptable to the Administrator;

-a pressure-relief valve may be serviced, repaired, set, or

sealed only by a person who holds a Certificate of Authorization

Permit described in.


♦ Section 11 and who complies with Section 13.

-Online Visual Examination

-A online external visual examination of pressure-relief devices shall be carried out by a competent person at appropriate intervals, based on the pressure-relief device history.

-The maximum interval for this on-stream examination is five years.

-The scope of this examination shall ensure that:

-the correct device is installed and that the seals are intact;

-there is no external damage or leaks;

-the company identification provides means to establish the last servicing date and correct set pressure for the equipment protected by the device;

-there are no blinds or closed valves that would prevent the device from functioning;


-any isolating valves in the path of relief valves are locked and

controlled;

-discharge piping is secured and clear; and correctly installed to

prevent build up of liquids;

-any weather protection is in place;

-suitable records are maintained to document the on-line visual

examination;

-any lifting lever is operable and positioned correctly; and

-any rupture disc is properly installed and oriented.

-Pressure Equipment Inspection & Servicing Requirements AB-

506, 2009-05-29 Revision: 6 Page 27 of 34

Absa, AB506…..…….Contd.11

♦ 17.3 Pressure Relief Valve Servicing Intervals

♦ Table 1, shows the maximum periods of time a pressure-relief valve may remain in

service before it requires servicing, unless it has been deferred or revised in

accordance with Section 15.

♦ The term pressure-relief valve (PRV) applies to safety valves, safety relief valves, and

relief valves. The applicable progressive interval grading and known service

requirements covered in Section 12 shall be used to determine servicing

interval for pressure relief valves.

♦ The interval grading system does not apply for thermal relief valves and other

protective devices not classed as pressure relief valves. These shall be inspected,

tested and serviced/replaced at appropriate intervals based on their service history.

♦ PRV s must be serviced by an organization that has a valid ABSA Certificate of

Authorization Permit to service pressure-relief valves. It is the owner s

responsibility to ensure that the organization servicing the PRV is competent for the

scope of work. Authorized PRV-servicing organizations are listed on the absa.ca


♦ The owner must have appropriate work processes, methodology, and assessments to ensure that the intervals assigned are appropriate. The servicing interval shall be based on the history in a particular fluid service, cleanliness, and other servicing information. It shall also be assessed by performing an as-received pop test (pre-test). This is required for all process valves, unless the valve is extremely fouled and dirty or if a valve is in a hazardous service that may require neutralizing. When a valve is replaced it may still need to be assessed through pre-pop, dismantling etc. in order to establish a suitable interval for the valve that has been installed (refer to API RP-576).

♦ When a pressure-relief valve servicing report indicates the valve was in unsatisfactory condition when it was removed from service, a lower interval may be required. The owner should conduct a root cause analysis for the purpose of preventing reoccurrence, because reducing the length of the service interval may not always address the cause.


♦ This is particularly important when the valve fails the service

pre-pop test or is otherwise found to be in an inoperable

condition.

♦ Appendix B shows factors that may need to be considered when

assigning servicing intervals for pressure-relief valves.

♦ Servicing records and other data must be reviewed by the

Inspector, except as otherwise specified per the owner-user s

quality management system. The assigned servicing interval

must be approved by the Inspector.

♦ Servicing records and other required information to support the

assigned servicing intervals must be maintained on file.


♦ 17.4 Rupture Discs

♦ The device must be inspected at the assembly stage to

verify that it has been installed correctly and that the

disc meets the requirements defined in Section VIII,

Div. 1.

♦ Rupture discs shall be inspected and replaced at

scheduled intervals, based on the applicable

manufacturer s recommendations and equipment

history.

♦ The owner shall maintain documented work processes

to ensure the correct rupture discs are installed and

maintained safely.

Absa, AB516

♦ Clause 37 Owners responsibility

♦ Clause 38 Over pressure protection

♦ Clause 39 Pressure Relief Valves

♦ Adjustable parts of a pressure relief device must be sealed at the time of servicing and remain sealed during operation.

♦ Seals must be installed in a manner that prevents changing the adjustment of a pressure relief device without breaking the seal.

♦ A pressure relief device must be serviced at an interval acceptable to the Administrator.

♦ A pressure relief valve may be serviced, repaired, set or sealed only by a person who holds a certificate of authorization permit described in section 11 and who complies with section 13.

Absa, AB516…..…….Cont.2

♦ Any change to the adjustable parts of pressure relief devices

must be done on a controlled basis, as this can affect system

operation and safety. Adjustments must be made by a

competent person who holds any required qualifications

under the Act.

♦ For servicing intervals, see policy document AB-506,

Inspection and Servicing Requirements.

♦ 17.3 Pressure Relief Valve Servicing Intervals

♦ Table 1, shows the maximum periods of time a

pressure-relief valve may remain in service before it

requires servicing, unless it has been deferred or

revised in accordance with Section 15.


♦ The term pressure-relief valve (PRV) applies to safety

valves, safety relief valves, and relief valves. The

applicable progressive interval grading and known

service requirements covered in Section 12 shall be

used to determine servicing interval for pressure relief

valves.

♦ The interval grading system does not apply for

thermal relief valves and other protective

devices not classed as pressure relief valves.

These shall be inspected, tested and

serviced/replaced at appropriate intervals based

on their service history.


♦PRV s must be serviced by an organization that

has a valid ABSA Certificate of Authorization

Permit to service pressure-relief valves. It is the

owner s responsibility to ensure that the

organization servicing the PRV is competent for

the scope of work.

♦Authorized PRV-servicing organizations are

listed on the absa.ca website.


♦ The owner must have appropriate work processes, methodology, and assessments to ensure that the intervals assigned are appropriate. The servicing interval shall be based on the history in a particular fluid service, cleanliness, and other servicing information. It shall also be assessed by performing an as-received pop test (pre-test). This is required for all process valves, unless the valve is extremely fouled and dirty or if a valve is in a hazardous service that may require neutralizing. When a valve is replaced it may still need to be assessed through pre-pop, dismantling etc. in order to establish a suitable interval for the valve that has been installed (refer to API RP-576).

♦ When a pressure-relief valve servicing report indicates the valve was in unsatisfactory condition when it was removed from service, a lower interval may be required. The owner should conduct a root cause analysis for the purpose of preventing reoccurrence, because reducing the length of the service interval may not always address the cause.


♦ This is particularly important when the valve fails the service

pre-pop test or is otherwise found to be in an inoperable

condition.

♦ Appendix B shows factors that may need to be considered when

assigning servicing intervals for pressure-relief valves.

♦ Servicing records and other data must be reviewed by the

Inspector, except as otherwise specified per the owner-user s

quality management system. The assigned servicing interval

must be approved by the Inspector.

♦ Servicing records and other required information to support the

assigned servicing intervals must be maintained on file.

♦ Pressure Equipment Inspection & Servicing Requirements AB-

506 - 2009-05-29 Revision: 6 Page 28 of 34

Absa, AB516............Contd.7

♦ 17.4 Rupture Discs

♦ The device must be inspected at the assembly stage to verify that it has been installed correctly and that the disc meets the requirements defined in Section VIII, Div. 1.

♦ Rupture discs shall be inspected and replaced at scheduled intervals, based on the applicable manufacturer s recommendations and equipment history.

♦ The owner shall maintain documented work processes to ensure the correct rupture discs are installed and maintained safely.


♦ 18.0 REPAIRS AND ALTERATIONS OF IN-

SERVICE PRESSURE

♦ EQUIPMENT

♦ PESR Section 40 covers specific requirements for

repairs and alterations to in-service pressure

equipment.

♦ AB-513 has been issued by the Administrator to

provide guidance on the application of requirements

established in the (PESR). AB-513 provides detailed

information on the inspection and certification

requirements for repairs and alterations

Absa, AB-524

♦ The AB-524 requirements becomes mandatory effective January 1, 2014.

♦ The period until December 31, 2013 is expected to be utilized by the

♦ industry to:

♦ implement and practice the requirements;

♦ identify gaps in their QMSs, take corrective action and upgrade the

equipment as necessary to ensure compliance by January 1, 2014;

♦ validate the effectiveness of the requirements and provide feedback to

ABSA to help improve the requirements.

♦ In order to assist the industry achieve compliance by the mandatory date of January 1, 2014, ABSA will conduct audit of each certified shop by Dec. 31, 2013 and provide feedback to the auditors in regards to the gaps between their current practices and the requirements.

Absa, AB524..……….Contd.2

♦ 3.0 Key Requirements:

♦ CAP is required to manufacture, assemble, repair, service, set or seal PRDs (PESR 11).

♦ The design of PRDs must be registered with ABSA (PESR 14 and CSA 4.2)

♦ CRN must be stamped on the PRD s Name Plate (CSA 5.1.1)

♦ PRDs must be ASME Code stamped (CSA 5.3.1)

♦ Pressure equipment must be protected by PRVs or other means of overpressure protection acceptable to the Administrator [PESR 38(1)].

♦ A PRD must be set to open before the pressure in the pressure equipment exceeds the MAWP of the pressure

……equipment [PESR 38(2)].

Absa, AB524..……….Contd.3

♦ Overpressure protection system must be designed and

maintained so that maximum pressure in the pressure

equipment does not exceed the prescribed limit of

overpressure allowed in the applicable code declared

in force by the PESR [PESR 38(3)].

♦ Adjustable parts of PRDs must be sealed at the time of

servicing and remain sealed during the operation

[PESR 39(1)].

♦ A PRV must be serviced.


♦ The following codes and standards include requirements for Pressure Relief Devices and have been adopted through the PESR (Sec. 6 of PESR).

♦ Compliance with the requirements of the adopted codes is mandatory: CSA B51, Boiler, pressure vessel and pressure piping code: CSA B51 Code establishes requirements for the construction and servicing of Pressure Relief Devices in Canada. The code has been adopted by all pressure equipment jurisdictions in Canada and therefore compliance with it is mandatory throughout Canada (the application of the requirements may vary). Requirements regarding the design registration [Canadian Registration Number (CRN)], Clauses 4.1, 4.2 and 4.3; quality control program and registration with the local pressure equipment.

♦ Jurisdiction for manufacturers and servicing organizations…..

Absa, AB524……….Contd.5

♦ The pressure equipment safety authority {ABSA:

D0264943.DOC .7}AB-524 Edition 2, Rev 0 Issued

2013-01-01 Page 12 of 45.

♦ dismantle and inspect the internals before cleaning

and servicing, and, record the observations in the

service report; service and/or repair the PRV;

♦ re-set the set pressure of the PRV when requested by

the owner and record the new settings in the service

report. A Repair Name Plate shall be

♦ securely installed beside the original name plate;

replace parts and record the information in the service

report. OEM parts must be used;


♦ Organizations who manufacture, assemble, inspect, repair, service, set or seal PRVs are required to understand and have access to a current copy of this Code.

♦ ASME Section I, IV, VIII-1, VIII-2, VIII-3 Codes:

♦ ASME Sections I, IV, VIII-1, VIII-2, VIII-3 Codes include requirements for the manufacturers and assemblers of PRDs. The requirements cover design, manufacturing, assembly, materials, welding, examination, testing and certification of PRDs.

♦ All of the requirements included in the ASME Codes are mandatory for the manufacturers and assemblers. Many of those requirements are also mandatory for the servicing organizations.

♦ Manufacturers and assemblers are required to understand and maintain current copies of the applicable ASME Codes. Repair and Servicing organizations are required to understand and have access to the current copies of the applicable ASME Codes.


♦ Manufacturers and assemblers are required to understand

and maintain current copies of the applicable ASME Codes.

Repair and Servicing organizations are required to

understand and have access to the current copies of the

applicable ASME Codes.

♦ ASME PTC-25, Pressure Relief Devices Performance Test

Code:

♦ ASME Sections I, IV and VIII-1 Codes state that the definitions

relating to pressure relief devices in Section 2 of ASME PTC 25

shall apply.

♦ Organizations who manufacture, assemble, inspect, repair,

service, set or seal PRVs are required to have access to a

current copy of this Code.


♦ NBIC 23, National Board Inspection Code:

♦ The National Board Inspection Code, NBIC-23 provides

technical guidance for maintaining the integrity of in-service

pressure equipment and servicing the PRVs. NBIC is not

mandatory in Alberta. Companies who meet the requirements

of NBIC, NB s rules, and, when certified by the NB, are

permitted by NB to apply the VR stamp to the serviced PRVs.

NBIC is considered as a recognized and generally accepted

good engineering practice by the pressure equipment

industry. Historically, the PRVs service industry in Alberta and

ABSA have closely followed the recommendations of NBIC.


♦ Organizations who inspect, repair, service, set or seal PRVs are

required to understand and maintain a current copy of the NBIC-23.

NB-18 National Board Pressure Relief Device Certifications:

♦ The publication lists the PRDs that are certified by NB. Each device

description includes information about the manufacturer, certification

number, design number, type of PRD, ASME Code of construction, test

medium, set pressure definition and blowdown. The publication is updated

♦ The pressure equipment safety authority

♦ {ABSA: D0264943.DOC .7}AB-524 Edition 2, Rev 0 Issued 2013-01-01

Page 11 of 45. Monthly and is available free of charge

from the NB website at ww.nationalboard.org.

♦ PRV repair and servicing organizations are

required to maintain access to a current copy of

NB-18.


♦ Codes and Standards referred to in the CSA and ASME

Codes:

♦ When other codes and standards are referred to in the CSA

B51 and applicable ASME Codes, compliance with those

codes and standards is mandatory. Examples of some of the

referred to codes and standards are ASME PTC-25, ASME

Section IX for welding, ASME Section V for NDE.

♦ API-527 for seat tightness testing, API-520 and API-521.

♦ When the referred to codes or standards form part of the

activities certified by the CAP, the understanding and

maintenance of the applicable sections of those codes or

standards is mandatory.


♦ API-576, API-520 Part I and Part II, API-521:

♦ API-576, API-520 Part I and Part II, API-521 standards are

recognized and generally accepted as good engineering

practice by the petroleum, process and PRD industry. API-576

Standard provides information about causes of improper

performance, inspection and testing methods of PRDs; API-520

Part I covers sizing and selection of PRDs; API-520 Part II

covers installation of PRDs and API-521 deals with design

criteria, causes of overpressure, relieving rates and disposal

systems.

♦ It is recommended that the organizations implement the

applicable practices of the API standards and maintain

current copies as necessary.


♦ Maintenance Manuals:

♦ Current editions of manufacturers maintenance manuals, drawings,

♦ specification sheets shall be maintained by the service organizations.

♦ Note: Electronic access in lieu of maintenance of hard copies is acceptable, provided the provision is described in the document control process.

♦ 3.3 Scope of Alberta's Bench Testing program:

♦ The scope of Alberta s Bench Testing program for in-service PRVs is limited to servicing, set pressure testing, seat tightness testing and sealing. Capacity and Blowdown tests are not within the scope of the program. When servicing in-service PRVs, all requirements of the applicable ASME Codes apply except for those pertaining to capacity and blowdown testing.


♦ When a PSV is received for servicing, the service

organization shall:

♦ inspect the PSVs in the as received condition at the service

shop and record the observations in the service report;

pretest the PRV to the tolerance limits specified by the

applicable ASME Code and to the set pressure definition as

defined in NB-18 or manufacturer s specifications. Record the

results in the service report;


♦ Conduct the set pressure test:

♦ After a PRV is serviced, parts repaired/replaced as necessary and assembled, it must be set and tested to the set pressure. The set pressure test shall meet the requirements of the set pressure definition specified in NB-18 or manufacturer s literature and the tolerance limits specified by the applicable ASME Code of construction.

♦ Conduct the performance test:

♦ Upon completion of the set pressure test, pressure shall be further increased to confirm that the PRV attains sufficient lift within the accumulation tolerances specified by the applicable ASME Code of construction.

♦ perform a seat tightness test in accordance with the requirements of the manufacturer or API-527 whichever is applicable and record the results in the service report; attach a service name plate (tag) in accordance with the requirements of

♦ Organizations QMS; seal the adjustable points; provide a service

……report to the owner.


♦ Test medium:

♦ 1. Air/gas PRVs:

♦ Bench testing: PRVs designed for air/gas medium shall be tested with air or a suitable inert gas at the service shop.

♦ Field testing using an assist lift device: Process fluid

♦ 2. Steam PRVs:

♦ Bench Testing:

♦ PRVs used in steam service shall be tested with steam except as

♦ follows:

♦ - ASME Section IV Code stamped heating boiler safety valves set at or below 103 kPa (15 psi) may be tested with steam or air.

♦ - O/Us who are certified by ABSA to service, set and seal their own PRVs may test and set ASME Section VIII-1 & 2 steam service PRVs with air provided the manufacturer s steam to air correction actor is applied. O/Us may get their PRVs set on air by an ABSA certified PRVs servicing shop provided the owner:

♦ - provides the documentation to the shop regarding the correction factor;

♦ - provides the manufacturer s procedures to the shop for applying the correction factor;

♦ - ensures that the PRV shop employs technicians who are trained in setting and testing the steam service PRVs with air.


♦ For PRVs used in steam service which could not be tested with steam

because of the limitations of the steam facilities at the service shop, the

PRV may be set with air at the shop provided the final set pressure

verification is done with steam at the owner s or other suitable steam facilities. Steam service PRVs set on air shall have a red tag attached,

warning the owner that final setting on steam is required. The red tag

shall be of min. 50mm x 75mm (2 x 3 ) size, made of durable material

that could not be easily ripped off and be substantially as shown in the

diagram.

♦ The red warning tag shall be securely attached with service

♦ company s seal and include the following information:

Required wording on the Front Side of the Red Tag:

WARNING

This PRV was set on air, final setting on steam required


♦ The name of the service company;

♦ Date

♦ Type/Model No.

♦ ASVS Number

♦ Required wording on the Back Side of the Red tag:

♦ This tag must be replaced with a Test Only tag after final setting on steam by an ABSA certified service company who conducted the test.

♦ If the PRV was serviced, the organization who serviced the PRV shall also install a Service Name Plate .

♦ Upon verification of the set pressure of the PRV with steam, the red warning tag shall be replaced with a Test Only Name Plate (tag) by an authorized service organization who tested the PRV with steam.

♦ It is permissible for one authorized organization to service the valve and another organization to set it with steam provided the activity is described in their respective written description of the QMS's.


♦ Field testing using an assist lift device: Steam.

♦ All ASME Section I PRVs in steam service shall be tested with steam.

♦ 3. Liquid PRVs:

♦ Liquid PRVs shall be tested with water or other suitable liquids except for

ASME Section IV Code stamped heating boiler safety relief valves set at or

below 1103 kPa (160 psi) which may be tested with water, steam or air.

♦ Verification Testing:

♦ During the audit the service organization shall demonstrate set pressure and seat tightness testing of one PRV each for each fluid service.

♦ 3.5 PRD design registration requirements:

♦ Design of a PRD shall be registered with ABSA. The registration of the design is the responsibility of the manufacturer. The registration of the design is indicated by the CRN stamping on the PRD s name plate. A CRN number must include a digit 2 or letter C after the period to be legal for use in Alberta.

Absa, AB524………..Contd.19

♦ Key documents and records: Examples of documents and records that may be controlled under this section include:

♦ - A written description of the QMS (electronic or hard copy)

♦ - Codes and standards

♦ - Manufacturer s maintenance manuals

♦ - Manufacturer s PRV specification documents

♦ - Manufacturer s drawings

♦ - Purchasing documents

♦ - Approved vendor s list

♦ - Planning documents

♦ - Contract documents

♦ - PRD specification sheets

♦ - PRV service sheets

♦ - PRD data sheets

♦ - Documents of external origin

♦ - Any other documents considered important by the organization

Absa, AB525

♦ Cases where the Use of PRVs is Mandatory

♦ The use of PRVs is mandatory for:

♦ A. Boilers (for example: ASME BPV Codes, Section I and Section IV require safety valves and do not consider the OPPSD principals);

♦ B. Boiler external piping as defined per ASME B31.1;

♦ C. Pressure vessels designed in accordance with paragraph UW-2(c) or (d) of ASME BPVC, Section VIII, Div. 1

♦ D. Pressure vessels in public occupancy;

♦ E. Fired-heater pressure coils;

♦ F. Thermal liquid heating systems; and G.Systems which, by virtue of potential chemical reactions, are not self limiting with respect to pressure.


♦ 5.0 Overpressure Protection Requirements

♦ Overpressure protection is considered the last line of defense against possible catastrophic failure of pressure equipment. The function of overpressure protection is to: Protect people, Prevent unsafe operation of pressure equipment, Protect equipment from failure due to overpressure, Prevent loss of production.

♦ Section 38(1) of the PESR requires that the owner of pressure equipment must ensure it has overpressure protection that is:

♦ (a) a pressure relief valve that meets the requirements of the ASME Code, or

♦ (b) other means of overpressure protection acceptable to the Administrator. According to the PESR, a pressure relief valve that meets the requirements of the ASME Code is required for protection of all pressure equipment unless the pressure equipment is protected by some other means acceptable to the Administrator. The Administrator may accept an alternative means of overpressure protection that is not a PRV, or the Administrator may issue a Variance for the means of overpressure

protection……


♦ or the Administrator may issue a Variance for the means of overpressure protection.

♦ Pursuant to Section 14(3) of the PESR, an applicant for the registration of a design must submit the information that the Administrator requires. Sections 14, 15, 16,17, and 18 of the PESR specify requirements for design registration.

♦ When the use of PRD, OPPSD, and/or other means of overpressure protection is considered to support pressure piping or pressure vessel applications, each design submission for registration needs to satisfy the design submission requirements specified in this document in addition to the requirements specified in the PESR and the code of construction.

Field Inspection

• Inspection of Valve - Do a visual inspection of the inlet and outlet. Many

types of deposits or corrosion products may be loose and may drop out during

transportation.

• Inspection of Adjacent Inlet and Outlet Piping - As soon as the

PRV is removed, the upstream and downstream piping should be checked for

corrosion, indications of thinning, and deposits that could interfere with valve

operation.

• Transportation of Valves to Shop - Before shipping the valve, flange

faces should be arranged to protect gasket surfaces. The valves should be

transported in the upright position. Rough handling can change the set pressure

or otherwise damage internal parts.

Corrosion

Nearly all types of corrosion are present in petrochemical service.

• Pitted or broken valve parts.

• Deposits of corrosive residue.

• Deterioration of the materials.

• Exposed studs vulnerable to

environmental corrosion

attacks.

Corrosion can usually be slowed or

stopped by the selection of more

suitable valves or valve material. Also

by better workmanship in the shop’s

maintenance and repair section. A

bellows seal can be used to protect the

internals.

Damaged Seating Surfaces

Many Causes of Damaged Seats

• Corrosion

• Foreign Particles (scale, deposits,

dirt, slag, etc.)

• Chatter ( inlet pressure drop)

• Careless handling

• Start-up leakage

• Alignment

• Incorrect ring settings

Failed Springs

1. Weakening of the Spring

(reduction of set pressure or

premature opening).

2. Total Failure (uncontrolled

valve opening.

Failed springs are almost always caused by

corrosion.

• Surface Corrosion

• Stress Corrosion

Where corrosion prevails:

- Change spring material

- Install bellows

- Spring coating

Plugging and Sticking

Solidified

products can

plug various

parts of the

valve and

connecting

piping.

Sticking of

internal parts

caused by

corrosion,

foreign particles

or poor

alignment

causing galling.

Balanced Bellows

All Bellows valves should

have bonnet open to

atmosphere however, if in

sour gas application,

should be vented to safe

area.

Balanced Bellows

Operators should be aware of

bellows equipped valves to

ensure vent plugs are

removed. Failure to do can

result in increased

backpressure and failure to

open at designated set

pressure.

Piping on Inlet/Outlet

Swage

Vessel

PSV

Check to ensure inlet piping isn’t

increased in size from the vessel outlet.

This can cause a failure to relieve

properly because of backflow within the

nozzle area.

Check for reduction in

the outlet piping size. This

can create a massive

difference in capacity of

the valve.

Misapplication of Materials

If ordering new valves or replacement valves, your vendor

would need to know if there are special applications to

consider such as:

-temperature (compressors can have high temps on their

psv’s)

-vibration (some styles of valves are more susceptible to

vibration damage)

-special process (e.g.. Stainless steel can’t be used on

chlorides)

Care must be taken to record the identity and location of

valves where special materials are required.

More Causes…….

• Rough Handling- dropping from treaters

• Improper Operating Gap- too close to set pressure

• Improper Location, History or Identification

• Improper Installation- too much strain on flanges

• Improper Valve Design

Pre-Testing & As Found Condition

• The valve is placed on the test

stand and pressured to find its

“as received” relieving pressure

(Pre-Test). The purpose is to

determine if the valve would

have worked in its immediate

application.

• This is critical for developing a

time frame for the next service

date.

• As found condition

determines if extensions or

decreases in service time frames

are to be considered.

HANDLING PSVs

♦ ALL PRVs must be treated as sensitive, pressure

monitoring devices.

– Frequently valves which are dropped, damaged, or handled

poorly, do not operate properly when reinstalled.

HANDLING PSVs

The tubing on a pilot valve

is critical to the operation

of the valve.

Carrying the pilot by the

tubing can often cause a

leak in the connection

thereby creating a potential

failure.

Always carry the pilot

valve using properly

installed lifting eyes or, by

the flanges.

HANDLING PSVs

Carry flanged valves

by the flanges or by

the pallet, if it is

mounted on a pallet.

This avoids the

potential of

grabbing in an area

where you could

break the seal wire

or put pressure on

the lift handle.

HANDLING PSVs

What not to do when Handling PSV’s

• Do not DROP Valves from any height.

• Do not LIFT more than you physically are

able.

• Do not THROW valves into shipping crates.

• Do not LIFT valves by the lifting lever.

• Do not RIG valves in or out without proper

equipment.

• Do not break Wire Seals on PSV’s

This Valve is not being

Handled Correctly

HANDLING PSVs

♦ The owner / user must insist that all PRV’s (new or serviced) arrive onsite in a vertical position.

♦ This assures that the internal components remain properly aligned and protected.

HANDLING PSVs

♦ The installer must ensure that proper lifting equipment is used

when removing and reinstalling PSVs.

♦ The owner / user may even consider the installation of special

lifting eyes on those valves which are high up or located in

difficult spots.

♦ NEVER use the lift lever as a handle or a lifting hook for a web

sling as this will cause damage to the valves operation.

HANDLING PSVs

♦ The installer must ensure that proper lifting equipment is used when removing and reinstalling PSVs.

♦ NEVER use the lift lever as a handle or a lifting hook for a web sling as this will cause damage to the valves operation.

HANDLING PSVs

HANDLING OF PSVs

♦ Ensure that all inlet and outlet gasket surfaces are clean and will seal properly.

♦ Also note the internal surfaces must be inspected for contamination.

HANDLING PSVs

Ensure you use

the correct

gasket for each

flange size so

there is no

restriction of

the inlet/outlet

and no

interference

with the bolt

holes.

HANDLING OF PSVs

♦ When installing a threaded valve, use the hexagonal base to tighten onto the threaded pipe connection.

♦ Remove the valve in the same way.

♦ Never use a pipe wrench on the body of a pressure relief valve.

HANDLING OF PSVs

♦ The seal is the OEM or repair facility's way of guaranteeing you the valve has been assembled or serviced by a national board Certified / A.B.S.A. Registered Safety Valve repair shop.

♦ It is imperative that the seals are not broken no matter where they are located.

♦ If the seal is broken it voids any assurance that the valve has not been tampered with by others.

♦ Although someone might accidentally break the seal during installation it will still be necessary to recertify the valve before a new seal is installed.

HANDLING OF PSVs

Bonnet cap seals Blowdown ring locking screw

HANDLING OF PSVs

Ensure all plugs are removed from the outlets of threaded valves.

When left in, they act as a plug on the valve and can prevent the valve from relieving pressure when overpressure situation occurs. (Becomes a potential bomb)

Transportation

Poorly shipped PSV’s. This delivery should be rejected by receiving

deptt at plant site

Inspection Examples

Bolts in vibrating

service should

be checked for

fretting and

adequate to

ensure proper

tightening.

(no short bolting)

Installation Examples

What can happen when heat tracing

is not operating?

Before

After

141

Good “triangle”

Support



Any pressure changes on Pressure

Relief-Safety Valves have to authorized

by your company Engineer or by

someone in authority who can sign

appropriate forms. This is required by

ABSA to prevent a pressure change to

greater than the vessel is rated for.

A second data plate is required to show

new pressure, capacity, part number,

and date of change.

PSV Name Plate Information

What can be

right here?

Installation

Examples

Handle should

be oriented

downward to

prevent accidental

closing due to

vibration,

gravity, etc.

We can

avoid this?

Examples

Will these bolts

Hold when the

PRV relieves?

Certainly we

can avoid

this, Isn’t it?


Long

Unsupported

Moment

Arm

What can be

improved

here?

Examples

Discharge too

near deck

What can be

improved

here?


Discharge

directed

downward


Criteria in Setting up of

Pressure Relief Valve in

Process Piping and

Systems of Operations in a

Plant


♦ Criteria in setting up PSVs

-Single PSV : Allowable overpressure is 10% or 3psi,

which ever is greater.

- Multiple PSVs:

- 1st Valve: Maximum Set: MAWP is allowable

overpressure:16%

- 2nd Valve: Maximum Set:105% MAWP is allowable

over pressure:10.48%

Pressure Requirements per Code

Pressure Relief Valve

Characteristics

Pressure Relief Valve

Characteristics

Vessel

Pressure

%

Maximum

Allowable

Accumulation

, nonfire

Maximum

Allowable

Working

Pressure

(MAWP)Set Pressure

Reset

PressureOperating

Pressure

(Any Practical

Level below

MAWP)

OVERPRESSURE

120

115

110

105

100

97

90

ACCUMULATION

BLOWDOWN


Fire Sizing

♦ Fire Gas Expansion: Assumes the protected vessel is

filled with gas.

♦ Fire Vapor Generation: Assumes the protected vessel

is filled with liquid. There are three possible

scenarios:

-Know the capacity.

-Know the wetted surface area.

-Know the vessel dimensions.


♦ The Procedure used in fire sizing depends on the

Codes and Engineering practices applied at each

installation. Some procedures that may be used for fire

sizing codes and standards are:

♦ API RP520, Part1

♦ API 2000

♦ NFPA 58

♦ CGA S-1.3


♦ Criteria in setting up PRVs for FIRE Case Scenario is:

-Single Valve: Allowable overpressure is 21%

-Multiple Valves: Maximum SET:

1st valve : MAWP

2nd Valve : 110% of MAWP

-Allowable Over pressure.

1st Valve : 21%

2nd Valve : 10%

Pressure Pulsations

Set Pressure MAWP

Leaks

Metal-Seated Spring PRV Pilot Operated PRV

Probable

Premature

Relief Cycles

And

High Maintenance

10%

5%

Operating Pressure

(Pos. Displace. Comp.)

Tight


Protected System

PRV

An Ideal Pressure Relieving Device should

be:

LEAK-FREE TO SET PRESSURE

OPENS AT SET PRESSURE

RELIEVES ONLY THE INPUT INTO

THE PROTECTED SYSTEM

STABLE DURING RELIEF CYCLE

RE-CLOSES AT SET PRESSURE

(0% BLOWDOWN)


Types of Pressure Relief

Valves and Applications


♦ Types and applications:

Petrochemical industry

Chemical industry

All applications where

API is specified



Chemical industry

Heating, Venting, Air conditioning

(HVAC)

Power plants (ASME VIII)

Paper industry



Chemical industry

LNG / LPG / Cryogenic systems

High pressure

Technical gases



Food and Beverage industry

Pharmaceutical industry

Cosmetic industry

Chemical industry



Chemical industry

High corrosive applications


♦ Types and Applications:

Thermal expansion

Pumps and

compressors


♦ Components and Industry Options:


API Style Vs High Performance

Style


Elastomeric bellow: -Protects the moving parts and spring against dirt, corrosion,

impurities and the fluid itself.

-Set pressure range: p < 10 bar / 145 psig

ATTENTION: Elastomer bellows can not

be used for back pressure compensation.

Steel Bellows: -Prevent changes in set pressure when the valve is

subjected to variable back pressure.

-Isolate the bonnet chamber and spring

against dirt, corrosion, impurities and

the fluid itself.

-Should be used at variable superimposed

back pressure or if the built up pressure

Exceeds 15 % of the valve set pressure.


Manufacturing Industry offers

options / features to Pressure

Relief Valves such as:


♦ To prevent leakage and costly product loss as well as reduce

downtime and maintenance costs, it is important to select

appropriate sealing surfaces such as:

- Stellited

- O-ring disc

- Vulcanized soft seats

- Sealing plate


Other /more options in Pressure Relief/Safety Valves are:

♦ Heating jacket

♦ Open bonnet

♦ O-ring disc

♦ Sealing plate

♦ Disc stellited

♦ Screwed cap

♦ Plain lever

♦ Packed lever

♦ Bolted cap

♦ Bolted lifting device

♦ Drain hole

♦ Stainless steel bellows

♦ Test gag

♦ Lift indicator

♦ O-ring-damper


♦ Lifting Devices: Open Vs Closed NOTE : ASME Code states that a lifting device must be used on:

air, steam and hot water applications over 140° F.


♦In applications with highly viscous fluids (low Reynolds

number)

a heating jacket with heated spacer ensures:

– The proper function of a safety valve

– The safety valve will not clog


Change-over valves serve to connect two safety valves to

a pressure system. One safety valve is in operation and the other

one is on standby.

The standby safety valve can be disassembled and maintained

during the running operation – the protection of the pressure

system against incorrect pressures remains guaranteed.

♦Advantages:

– Continuous operation

– Easy handling

– Robust design


Change over valves are used in multiple processes applications :

■where a shut down of the plant is not possible

■where a shut down of the plant is not desired due to a high technical effort. By switching off the plant media could e.g. harden, cement or congeal.

■where a shut down of the plant is not wanted in order to guarantee a continuous operation, e.g. in natural gas storage tanks or refineries to increase the time between scheduled shutdowns.


Symptoms of Pressure

Relief Valves


Leakage

♦ Symptom 1 The safety valve seat is leaking .

♦ Symptom 2 The safety valve body or shell is leaking.

♦ Symptom 3 The safety valve is simmering.

Opening/ Closing

♦ Symptom 4 The safety valve opens too early.

♦ Symptom 5 The safety valve opens too late .

♦ Symptom 6 The safety valve does not open .

♦ Symptom 7 The safety valve closes too late .

♦ Symptom 8 The safety valve does not close .


Operation/ Function

♦ Symptom 9 The safety valve is chattering/ fluttering .

♦ Symptom 10 The safety valve is fully open; pressure is rising above

max. relieving pressure.

♦ Symptom 11 The safety valve does not achieve required lift .

Corrosion/ Wear

♦ Symptom 12 The safety valve shows strong internal corrosion .

♦ Symptom 13 The safety valve shows strong external corrosion.

♦ Symptom 14 The safety valve shows wear between spindle and

guide.

♦ Symptom 15 The safety valve shows damaged sealing surface.


Special Applications

♦ Symptom 16 The stainless steel bellows fails

regularly .

♦ Symptom 17 The safety valve cannot be lifted

manually .

♦ Symptom 18 The safety valve cannot be lifted

pneumatically (Lifting device H8)


♦ Formation of Hydrates result from water contamination. When a SRV/PRV relieves, depending upon Set Pressure, Backpressure and Temperature, the hydrates may fall out as a liquid, even a solid.

♦ For Conventional Oil and Gas Work

- If they fall out as a liquid, use 'self draining' body design.

- If they fall out as a solid, it could possibly clog the valve. If ice forms on the Disc, a Soft Seat may help but not necessarily solve the problem.

- The major concern would be clogging of the discharge area of the valve. Heat would then be required in the form of either Heat Tracing or Jacketing.


♦ For SAGD work

- The only issues We have had with hydrates

forming in a relief valve were in a pilot valve

where chlorides dropped out of steam as it

condensed in the dome of the main valve. This

caused issues to all of the 316SS fittings.


♦ Pressure Relief

♦ The body cavity between position-seated dual-seal valves may trap oil or product. When the body cavity is exposed to direct sunshine, the trapped oil expands, and excessive pressure builds up inside these cavities. Pressure mitigation is thus required.

♦ The Project Engineer shall ensure that adequate valve-body pressure-relief capability is provided. For most position-seated dual-seal valve types, pressure relief is normally an integral part of the valve seat design, and no external piping is required. When such integral pressure relief is not provided, all above-ground, torque-seated DB&B valves (i.e., expanding plug, compact expanding gate, and expanding gate valves), as well as ball valves utilizing two dual-piston effect seats, shall require external piping to relieve body-cavity pressure. External pressure-relief auxiliary requirements are identified.


Pressure relief is generally not required for buried

service.


♦ To relieve body-cavity pressure, Company preference is for relief lines to be routed to the energized side of the valve (i.e., the source of the process medium that is being isolated). This routing helps to ensure that any leakage past the seal on the energized side of the valve is not released to the non-energized side of the valve which requires isolation.

♦ Comment: Failure to relieve the differential pressure may result in excessive pressure build-up in the body cavity, which usually puts undue stress on shaft seals and packing. When pressure relief is not inherent in the valve design (i.e., position-seated dual-seal valves or ball valves with a self-relieving seat), the preferred pressure-relief configuration is to use tapped connections in the valve body and an external pressure-relief device installed by the manufacturer.


♦ In ball valve applications where external pressure

relief is not required (i.e., where a self-relieving seat is

specified), the valve shall be clearly tagged with an

indication of the direction of relief (upstream or

downstream).


♦ Drain and Bypass Connections

♦ Draining of a valve cavity may be required to minimize product

contamination and possibly bleed pressure in the valve cavity.

♦ The size and location of the drain connection shall be indicated.

The drain connection shall be at the lowest point of the valve in the

installed configuration and shall be externally protected.

Antistatic Provision

♦ When not inherent in the valve design, antistatic provision shall be

required to provide electrical conductance between the

gate/ball/plug/disk and the body to prevent any electrostatic charge

build-up during fluid flow and valve operation.


Common causes of overpressure are:

- Discharge blocked.

- Thermal expansion or change in pressure.

- Failure of a control valve.

- External factors such as fire, excess flow.

- Improper sizing at the replacement of valve.

- Sudden increase in capacity/production.


Maintenance Requirements of Pressure Relief Valves

Owner is responsible to maintain per Absa AB505

and 524 Guidelines


♦ Reason why the valve is being serviced

♦ Owner servicing interval policy

♦ Alberta AB-506 PRV mandatory requirements

♦ Condition of inlet and discharge piping

♦ Fouling condition of PRV prior to dismantling

♦ Bench test prior to dismantling

♦ Conditions of parts and internal fouling

♦ Historical performance of PRV

♦ Fluid Service, - change, -same

♦ Consequence of failure, Environment, Safety, Economic.

♦ NOTE: NEXT PRV SERVICING INTERNVAL ASSIGNED Effective root-cause analysis and corrective and preventive action processes must

be in place to address any operational and condition problems identified.


♦ Routine maintenance requirements are:

- Cleaning.

- Disassembly.

- Maintenance.

- Reassembly.

- Component inspection.

- Testing for correct operation.

- Leak testing.


Absa issues a news letter called :

“ The Pressure News” it is free and it is a good

engineering practice to read that and subscribe to

Absa news letter for update/s.

Absa issues Bulletins and Alerts related to Pressure

Relief Devices.

Absa issues PRD interpretations of the ASME Codes.

Absa issues selected PRD code cases published by

ASME.


Pressure Relief/Safety Valve, all it does is balance of internal process pressure.


Energy Lean

Management

Systems– Part 2


♦ Energy Lean Management – Part 2, Factors to establish in

determining Inspection Intervals of PRVs

- Probability of failure.

- Calculation of Risk.

- Planned inspection using Risk Matrix.

- Root Cause Failure Analysis.

- Historical background on any failure/s.

- Case Studies.

- Functional/operational reviews.


Energy Lean Management Systems Part 2

• PRVs Inspection Intervals – How do they get established?

• API 510 Inspection Code

– “pressure relief valves shall be tested at intervals that are frequent enough to verify that the valves perform reliably.”

– “Intervals between pressure relieving device testing or inspection should be determined by the performance of the devices in the particular service concerned and maybe increased to a maximum of 10 years”

– Latest version of 510 allows the use of Ris Based Inspection to set intervals.

• Inspection Programs per API 510 and Absa

– Conditioned Based (probability based)

– Set an Interval, inspect and adjust based on results of inspection

• API RBI methodology evaluates both probability and consequence,

i.e. risk-based.


Energy Lean Management Systems– Part 2

• API PRVs Methodology was included in the 2008 Edition of API RP 581

• Methodology has been incorporated into Version 8 of the API RBI software

• Methodology has been applied at numerous clients/plant sites with accurate results, proven and acceptable.



• High Quantitative: The Risk for PSVs are calculated for two failure

modes:

• 1. Fail to Open (FAIL)

– PSV does not open on demand during an overpressure scenario

(fire, blocked discharge, CV failure, loss of cooling, power failure,

etc.)

– Over pressures can be well over normal operating, for some

scenarios burst pressure (≈ 4 x MAWP)

– Evaluate loss of containment (leaks or ruptures) from the protected

equipment at the overpressure calculated for each applicable

overpressure scenario.

– Includes repair costs of equipment, personnel injury, environmental

and production losses



2. Leakage Failure (LEAK)

– PRVs leaks in-service

– Considers cost of lost fluid inventory, repair costs,

production losses if downtime is required to repair PRV

• RISK = Probability of Failurex Cost of Failure + Probability of

Loss x Cost of Lost, $/year



• Probability of Failure

– POF is probability of PVD failure to open during emergency situations

causing an overpressure situation in the protected equipment resulting in

loss of containment (failures/year)

– POFOD is the probability of the PRV failing to open on demand

(failure/demand)

– DR is the demand rate on the PRD or how often an overpressure situation

arises that causes a demand on the valve (demands/year)

− (GFF x DF) is the probability of failure (loss of containment) from the

vessel in its current damaged mode/state.



- Direct Link to Fixed Equipment (Equipment such as vessel and plan

Piping)

– Links PRV to the vessel inventory group, operating and design

conditions, fluid properties and most importantly to the damage

state of the protected equipment

– Recognizes the fact that damaged vessels are at higher risk to

failed PRD than undamaged vessels, current PRD module does not

consider the protected equipment damage state.

– Since the damage factor of the protected equipment increases as a

function of time so does the risk associated with the PRD

protecting, it allows risk ranking of PRDs versus fixed equipment.



♦ Calculate impact area (consequence area) of release of hazardous fluids such as :Flammable,Toxic, Non-flammable (splash, spray, physical explosion, BLEVE)

♦ Consequence areas are based on damage to equipment and serious injury to personnel

♦ Financial consequences include

– Replacement cost of damage equipment – Cost of business interruption – Potential injuries – Environmental clean-up costs

• Consequence areas due to the effects of pool fires, jet fires, VCEs, BLEVEs, fireballs, flash fires and toxic releases are ……………calculated.



♦ PRVs Risk Based Inspection Methodology Accounts for PRVs Criticality.

–Recognizes the fact that PRVs may have many different overpressure scenarios, some PRVs response more critical.

–Enables the criticality of the PRVs service to impact Risk, i.e. more critical services result in more risk.

–Links to protected equipment, PRVs protecting damaged equipment will get more attention .


Energy Lean Management Systems– Part 2 ● The calculation of risk for a PRD failing to open upon demand is

calculated for EACH applicable demand case using the demand rate, the probability of failure of the PRD and the calculated overall consequence of failure for the demand case as follows:

• The overall risk is then determined by adding up the individual risks associated with the applicable demand cases as follows:

where i represents each of the n number of applicable

overpressure demand cases



♦ Consequence of failure is not time dependent

♦ Probability of failure increases with time

– As equipment damage increases, equipment probability of loss of containment (GFFT X DF) increases

–Number of Demands on PRVs increases (DR increases)

– POFOD increases as PRV condition deteriorates

♦ Inspection interval for each PRV is determined based on a risk target

♦ A risk target of $25,000/yr has been successfully used at many sites

– Balances reduction in risk with reduced inspection costs when compared to conditioned based inspection program (API 510)

– Typically reduces risk by 65-75% while average inspection interval

increase 25%. And the risk target is ultimately a calibration

tool to manage risk.



♦ API/Absa Risk Based Inspection methodology for Pressure Relief Valves provides a rigorous quantification risk for process unit relief systems.

♦ Probability of Failure of a PRV accounts for previous inspection history, demand rates, and installation history etc. The addition of consequences, based on safety and financial impacts, provides a broad overall view.

♦ Directly linking fixed equipment and PRVs Risk Based Inspection reduces input requirements and helps to establish criticality and inspection requirement/s.

♦ The methodology has been successfully implemented at refineries, SAGD Plants, Upgraders and petrochemical facilitates throughout North America ,typical implementation results in Safety and risk reduction, further inspection interval optimization.


♦ Absa recommends a list of related documents:

♦ Safety Codes Act and Regulations

♦ Pressure requirement safety regulation

♦ Exemption order

♦ AB506, 524

♦ CSA B51-09 and CSA B52-05

♦ ASME Codes such as section I, IV, VII, VIII-1,2&3

♦ ASME B31.3, B31.1, PTC-25

♦ ISO4126-1,2,3,4,5,6,7,8,9 & 10, ISO23251

♦ CGA G-201/ANSI K61.1

♦ NFPA 58 & 59

♦ NB-23 & 18, AP 520-1, 520-2, 521, 526,527, 576,580,581


♦ Our list of valuable links to other industry-related websites.

♦ Absa – Alberta Boiler and Safety Authority.

♦ American Institute of Chemical Engineers (AICHE)

♦ American National Standards Institute (ANSI)

♦ American Petroleum Institute (API)

♦ American Society of Mechanical Engineers (ASME)

♦ American Society for Testing & Materials (ASTM)

♦ International Pressure Equipment Integrity Association (IPEIA)

♦ National Association of Corrosion Engineers (NACE International)

♦ Pressure Vessel Research Council (PVRC)

http://www.aiche.org/

http://www.ansi.org/

http://www.api.org/

http://www.asme.org/

http://www.astm.org/index.shtml

http://www.ipeia.com/

http://www.ipeia.com/

http://www.nace.org/

http://www.nace.org/

http://www.forengineers.org/pvrc


♦ Acknowledgement for providing pictures, data in preparation

of this presentation by:

♦ Leser Valves, Pentair Valves, Dresser Valves. Farris Valves

♦ Mercer Valves, Cross Instrumentation, Rupture-Pin

Technology Inc

♦ Absa/API/NBBPV/ASME/PVRC/IPEIA/ANSI/NACE.

♦ Industry peers and colleagues at Fluor Canada Ltd.

♦ Valve Manufacturers and Repairs.

♦ User Companies in North America(US, Canada & Mexico)

♦ Knowledge from codes and regulations by Gobind Khiani,

P.Eng., APEGA PDE members including organizing

committee. And All the others who made this presentation possible.


Together we can avoid/stop any over pressure in

Plant Piping.

Questions!!!!!!!!!


♦Connect with Gobind Khiani, P.Eng.,

♦LinkedIn:

ca.linkedin.com/in/gobindkhiani

♦Contact (403)850-6982

♦Email: [email protected]

♦ [email protected]

mailto:[email protected]

mailto:[email protected]

pressure relie

Documents

relieving pressure

design pressure

opening pressure

inlet pressure

downstream pressure

closing pressure

excess pressure

definition of set pressure