ASME and PED Requirements
for
Drum Level
Instrumentation
2017
Presented by: Amir Hedayatnia
Clark-Reliance Corp.
Topics
• Gage Glasses and Remote Reading Instruments
• ASME Code Section I Requirements for Drum Level Instrumentation (boilers that operate > 1 Bar G)
• Water Columns(Standpipes) and Water Gage Isolation Valves
• Requirements for Isolation Valves
• ASME CSD-1 Low Water Cutouts Applications
• ASME Section VII Recommendations for Proper Care of Power Boilers
• Common Code Violations (Illustrated)
• PED Requirements
ASME Code General Terms
Gage Glass
Direct Reading Indirect Reading
Remote Level Indicator
Direct Reading Gage Glasses
Tubular Glass
to 17 Bar G Bi-Color
(Ported)
to 206 Bar G Flat Glass
(Transparent)
to 132 Bar G
Prismatic
(Reflex)
to 24 Bar G
End-to-End Reflex Gage Glasses
Are Permitted
- - PG.60.1 Clarifies
the use of multi-
section gages
without overlap, due
to the light
refraction principle
- Transparent Type
Multi-section gages
do require a 25 mm
minimum overlap
Flat Glass Transparent Type Water Gage
Glasses with LED Illumination
Typical View of Water Level with no obstructions in the
viewing area. The gage must be illuminated, as needed
for the level to be readily visible by the operator.
Structural Webs are Prohibited
From Flat Glass Gages Designs
- These Webs may
mask the actual
location of the water
level
- The risk of Masking
the level is enhanced
on elevated gage
glass installations
Bi-Color Water Gage Principle of Operation
Water shows GREEN Steam shows RED.
Bi-Color Gages must be outfitted with an
illuminator to be Code Compliant
(Light refracts differently through water than steam
with glasses on specific angles)
Remote (Indirect) Level Indicator
Technologies
Differential Pressure
Conductivity
Magnetic Guided Wave
Magnetic Water Level Gages are Permitted
up to 62 Bar G
Magnetic Level Gage (equipped w/ 4-20 transmitter)
For Process
(Typical)
For
Power
Boilers
Indication Scale
External switches
Are not permitted
for control purposes,
such as
Low Water Cutouts
(PG-12 and PG-60)
Code Issues and Concerns for the Use of
Magnetic Level Gages on Boiler Drums Acceptable as an acceptable Indirect Reading for applications range
up to 62 Bar G), Ref: PG12.2
The Indication Scale must follow ASME guidelines, Ref: PG-60.3.2 &
PG60.3.3
May not be used to support a water Gage glass, due to prohibition of
stainless steel construction for water columns. Ref: PG-12.3
No accessories are permitted to be attached for control purposes
(No Trip limiting switches). This device must be used for indication only. Ref: PG-60.1.1.4
The use of a Magnetic Level Gage does not replace the Code requirement for a Water Gage Glass on any Power Boiler Drum designed to meet Section I of the ASME Code
Section I Requirements
Operating up to 27 Bar G
One Direct Reading Gage Required (which must be kept continuous service)
Operating over 27 Bar G
Two Direct Reading Gages in service
or
Two Remote (Indirect) Level Indicators
On Continuous Display for the
Operator and One Direct Reading Gage (Which may be Isolated but kept in serviceable condition)
or
One gage glass in continuous service with a camera
system combined with an Indirect Remote Level
Indicator
Water Gage Requirements:
Section I Requirements for Gage Glass Placement
Level “A” = Lowest Permissible Water Level, at which
there will be no danger of overheating the boiler
Note: 4 and 6 must not intersect 1 and 2
1- Lower side
steam conn.
2- Upper side
water conn.
3- Level A
4- Low vision
5- Drum
6- High vision
7- Steam conn.
Section I - References
Water Columns (PG-60.2)
25 mm (1” min) connections for water column to boiler (PG-60.3.4)
20 mm (3/4” min) drain connection (PG-60.2.3)
Stainless Steel construction for water columns is prohibited (PG-12.3)
A Code stamp is not required on water columns, because they along
with level instruments are considered to be fittings (PG-11)
Water Level Indicators (PG-60.1) Water Gage Glass Requirements (PG-60.1.1)
20 mm (3/4” min) connection size for Remote (Indirect) level indicators (PG-60.3.4)
Highest & Lowest visible permissible water level (PG-60.1)
Isolation and Drain Valve Requirements (PG-60.1.2)
25 mm (1”) Gage overlap requirement for Transparent Gages (PG-60.1) - 1996
Transverse or Structural Webs are prohibited from the construction of Transparent
(Flat Glass) Water Gages, which may obstruct view of the level(PG60.1) - 2009
Stainless Steel is permissible for Gage Glass Body construction (PG-12)
Magnetic (Float Type) Level Gages are permitted up to 62 Bar G (PG-12) - 2007
Gage Cocks not required PG60.4 – 1991 (See image above )
Section I Valve Requirements
• Isolation valves installed between the drum
and a water column are optional and when
installed they must be locked open, to
prevent unauthorized use.
• Isolation (shut off) and drain valves must be
installed for any level indicating instrument
(Ref: PG-60.1.2)
• Drain valves must have an unrestricted 6 mm
(¼”) minimum opening
Globe Valves for Isolation
In-line flow prevents sediment or condensate traps, which can lead to false level indication with traditional Globe valves
Correct Incorrect
Globe type valves are permitted if the lowest edge of the seat is at least 25% of the port diameter.
(Ref: PG-60.3.7)
Specifying Ball Checks on Water
Gage Valves • Ball Checks are not mandatory on ASME Applications
• Ball Checks are mandatory on PED (European EN standards) and IBR (India) Applications
• Ball Check Valves (Reference: “Automatic Shutoff
Valves” in the Appendix of the ASME Boiler Code) and defines the design requirements for this User OPTION.
• Consider the application, before specifying Water Gage Valves with the Ball Check feature. The use of Chain operators improve safety by operating from a distance.
Ball Check Specifications, when Applied
Must have a
vertical rising
ball in lower
valve to prevent
trap of water in
gage glass
Typical upper
Ball check
shown
Always Install Chain
Operated valves for
Operator and Plant
Safety
PG.60.1.2 requires a
means to operate when
the valves are 2 meters
above the operating
floor or platform
ASME Section VII - Recommended Guidelines
for the Proper Care of Power Boilers
• Check water level in 2 or more instruments prior to start up and verify when a deviation is observed
• Keep Water Gage Glasses clean and easy to read, confirm there is no deviation that could be mistaken as water level
• Water Gages should be properly illuminated for easy observation
• Excessive blow down may cause premature wear of the gage internals
• Verification of high and low water alarms is critical to the prevention of carryover or damage to drum internals
Blowdown Procedure
Bypass Low Trip during this procedure
Common ASME Code Violations
and Concerns
• Isolated inoperable water gages
• Missing water gage glasses
• Missing illumination from water gages
• Inadequate display of remote level
indicators in the control room combined
with isolated gages
Code Violations
A drain valve is missing
on this lower water gage
valve
Magnetic Level Gage Scale
extends below lower connection,
it will always indicate some level
Photo of Serious Installation Error
Code Violation and Operation Risk to Boiler
Photo of Corrected Installation
Violation and Remedy
Before and After
ASME Summary
Requirements
• Code compliant material is used in all
pressure parts
• All welding procedures and personnel
are qualified
• All instruments are hydrostatically
tested at 1-1/2 times their design
pressure
PED Requirements for
Instrumentation
• EN12952-7 Subsection 5.4 requires a minimum of two Water Gage Glasses on all Power Boilers or one water gage combined with 2 Remote Level Indicators
• Connecting Tubes (Piping) between the
Boiler and the Water Level Indicator must have a minimum inside diameter of 20 mm
When the water connecting lines are longer than 750 mm, the inside diameter of the connecting piping must be at least 40 mm
Water connecting piping from the Boiler must always be horizontally oriented to the Water Level Indicators
PED Requirements for
Instrumentation
• 5.4.6 All Water Gage Glasses must be fitted with an internal Self-Closing Safety Device (Ball Checks in the Water Gage Isolation Valves)
• 5.4.5 On each Gage glass the Lowest Permissible Water Level shall be marked “LWL”
• 5.4.4 The lower limit of the gage glass range shall be at least 30 mm below the lowest permissible level
• The “open position” on Water Gage Cocks (Valves) shall be indicated
Compliance with PED
For All PED Categories:
• We conduct a PED Assessment using a
Program to evaluate the pressure and
volume of the instrument to determine
the PED Hazard Category
• Prepare a Declaration of Conformity
for Article 4 Par. 3 (most level
instrumentation), or Category I or II
Compliance with PED
• All Categories must be manufactured with
material including EN10204 3.1 rating
• On the MTR. All materials must be traceable
back to the European Community and
meeting all PED requirements.
• The final PED package (MDR) must be
retained for 10 years
Compliance with PED
Risk Analysis Form required for Category I and II includes:
Job # (Clark-Reliance Order Number)
Item # (Clark-Reliance Item Model Number)
Internal Pressure (pressure from the Hazard Calc.)
Operating Temp. (Saturated Steam Temp.)
Static Pressure & Volume of Contents:
- (Design Pressure & Volume of contents)
- This Form is signed by the Product or Quality
Manager
Compliance with PED
Complete a Final Internal and External Inspection Report
including:
– ‘Check’ drawings that go through our Shop with the
production documents.
– Each workstation initials they have witnessed or
completed ‘their’ responsibility for the equipment, we
are self certifying. This includes Dimensions, Welds,
Testing and Painting procedures
– These Check List drawings go to our Quality Dept. for
review and “sign-off”
Compliance with PED
Information Included in the Final PED Package:
• Weld Procedures (ASME – CAT. I or PED – CAT. II)
• Welders Qualifications
• Drawings with Weld Maps
• C-R ISO Registration Certificate
• Hydrotest Reports
Compliance with PED
Additional items that may apply (Cat I & II):
• Calibration Certificates for Torque Wrenches and Hydrotest Gauges
• Calibration PMA – Particular Material Appraisal required for each material on the order (Category I and II)
• Our QC Manual for Receiving and Inspection
• Instruction Manuals must be “CE” specific.
• Category I and II require PED tags attached to the instrument
Compliance with PED
Additional Requirements For Category II
• Must use PED Certified Welders
• Must have their PED Qualifications
• PED Welding Procedures must be reviewed by
an EU recognized Inspection Agency
Essential Information Required
for the Evaluation of
Applications
Specifications:
- Design Pressure
- Indication Range
- Vessel connection Size
- Vessel Connection Centers
- Application Environment
(Indoor or Outdoor)
Specify LED Illumination for Water Gage Glass applications for optimum view of the level Specify multiple technologies for Remote Indication to maximize reliability and protect against common mode failure
Recommend proper maintenance and routine inspection of these critical instruments
General Summary Recommendations for
Technology on Drum Level
Instrumentation
• All piping from the drum to the water
level instruments is to be insulated for the following reasons:
1. Provides safety for plant personnel 2. Increases level accuracy 3. Reduce excess condensate formation to improve instrument service life • Piping from Drum to Level Instruments
should be kept to a minimum < 2M
Recommendations for Level
Instrument Piping
Summary Your time and attention to this information is
appreciated, along with your contributions to
Operator and Plant Safety of Power Boilers
Questions
Request a copy at Clark-Reliance.com
Reliance Boiler Trim