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PTSC M&C ENGINEERING PIPING DESIGN TRAININGPIPING BASIC

DEFINITION AND DETAILS OF PIPES

NOMINAL PIPE SIZENominal Pipe Size (NPS) is a North American set of standard sizes for pipes used for high or low pressures and temperatures. The name NPS is based on the earlier "Iron Pipe Size" (IPS) system.That IPS system was established to designate the pipe size. The size represented the approximate inside diameter of the pipe in inches. An IPS 6" pipe is one whose inside diameter is approximately 6 inches. Users started to call the pipe as 2inch, 4inch, 6inch pipe and so on. To begin, each pipe size was produced to have one thickness, which later was termed as standard (STD) or standard weight (STD.WT.). The outside diameter of the pipe was standardized.As the industrial requirements handling higher pressure fluids, pipes were manufactured with thicker walls, which has become known as an extra strong (XS) or extra heavy (XH). The higher pressure requirements increased further, with thicker wall pipes. Accordingly, pipes were made with double extra strong (XXS) or double extra heavy (XXH) walls, while the standardized outside diameters are unchanged. Note that on this website only terms XS and XXS are used.

The NPS is very loosely related to the inside diameter in inches, and NPS 12 and smaller pipe has outside diameter greater than the size designator. For NPS 14 and larger, the NPS is equal to 14inch.For a given NPS, the outside diameter stays constant and the wall thickness increases with larger schedule number. The inside diameter will depend upon the pipe wall thickness specified by the schedule number.Summary:Pipe size is specified with two non-dimensional numbers,

nominal pipe size (NPS)schedule number (SCH)

NPS ½ ¾ 1 1¼ 1½ 2 2½ 3 3½ 4

DN 15 20 25 32 40 50 65 80 90 100

EXAMPLES OF ACTUAL INSIDE AND OUTSIDE DIAMETERSActual outside diameters

NPS 1 actual O.D. = 1.5/16" (33.4 mm) NPS 2 actual O.D. = 2.3/8" (60.3 mm) NPS 3 actual O.D. = 3½" (99.9 mm) NPS 4 actual O.D. = 4.1/2" (114.3 mm) NPS 12 actual O.D. = 12.3/4" (323.9 mm) NPS 14 actual O.D. = 14" (355.6 mm)Below you will find an example of the true inside diameters of a 1 inch pipe.

NPS 1-SCH 40 = O.D.33,4 mm - WT 3,38 mm - I.D. 26,64 mm NPS 1-SCH 80 = O.D.33,4 mm - WT. 4,55 mm - I.D. 24,30 mm NPS 1-SCH 160 = O.D.33,4 mm - WT 6,35 mm - I.D. 20,70 mm

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PIPE SCHEDULES

This is a number system setup by ANSI and ASME for the purpose of standardization to designate the size of a pipe. Pipe sizes are normally referred to as nominal pipe size (NPS). For pipe sizes from 1/8" thru 12" (nominal inside diameter), 14" and larger (actual outside diameter). The larger the schedule number the larger the pipe size. The 1/8" thru 12" diameters differ from the actual inside diameter.

Wall Thickness of Seamless and Welded Carbon Steel Pipe Schedule 5 Schedule 10 Schedule 20 Schedule 30 Schedule STD 40 - Standard Weight Schedule 40 Schedule 60 Schedule XH 80 - Extra Strong/Extra Heavy Schedule 80 Schedule 100 Schedule 120 Schedule 140 Schedule XXH 160 - Double Extra Strong/Double Extra Heavy Schedule 160

Wall Thickness of Stainless Steel Pipe Schedule 5S Schedule 10S Schedule 40S Schedule 80S

MATERIAL TYPESASTM GRADESDimensions from carbon steel pipes are defined in the ASME B31.10M standard, dimensions for stainless steel pipe are defined in the ASME B31.19M standard. The material qualities for these pipes are defined in the ASTM standards.These ASTM standards, define the specific manufacturing process of the material and determine the exact chemical composition of pipes, fittings and flanges, through percentages of the permitted quantities of carbon, magnesium, nickel, et cetera, and are indicated by "Grade".For example, a carbon steel pipe can be identified with Grade A or B, a stainless-steel pipe with Grade TP304 or Grade TP321 et cetera.Below you will find as an example a table with chemical requirements for pipe according to



ASTM A106 Grade A,B,C, and a table with frequent Grades, arranged on pipe and pipe-components, which belong together as a group.As you may be have noted, in the table below, ASTM A105 has no Grade. Sometimes ASTM A105N is described;"N" stands not for Grade, but for normalized. Normalizing is a type of heat treatment, applicable to ferrous metals only. The purpose of normalizing is to remove the internal stresses induced by heat treating, casting, forming et cetera.

Chemical requirements composition, %

Grade F304 (A) Grade F304L (A) Grade F316L (A)

Carbon, max 0.08 0.035 0.035

Manganese, max 2.00 2.00 2.00

Phosphorus, max 0.045 0.045 0.045

Sulfur, max 0.030 0.030 0.030

Silicon, max 1.00 1.00 1.00

Nickel 8 - 11 8 - 13 10 - 15

Chrome 18 - 20 18 - 20 16 - 18

Molybdenum - - 2.00-3.00(A) Nitrogen 0.10% max.

ASTM Grades

Material Pipes Fittings Flanges Valves Bolts & Nuts

Carbon Steel A106 Gr A A234 Gr WPA A105 A216 Gr WCB A193 Gr B7A194 Gr 2HA106 Gr B A234 Gr WPB A105 A216 Gr WCB

A106 Gr C A234 Gr WPC A105 A216 Gr WCB

Carbon SteelAlloyHigh-Temp

A335 Gr P1 A234 Gr WP1 A182 Gr F1 A217 Gr WC1 A193 Gr B7A194 Gr 2HA335 Gr P11 A234 Gr WP11 A182 Gr F11 A217 Gr WC6

A335 Gr P12 A234 Gr WP12 A182 Gr F12 A217 Gr WC6

A335 Gr P22 A234 Gr WP22 A182 Gr F22 A217 Gr WC9

A335 Gr P5 A234 Gr WP5 A182 Gr F5 A217 Gr C5

A335 Gr P9 A234 Gr WP9 A182 Gr F9 A217 Gr C12

Carbon SteelAlloyLow-Temp

A333 Gr 5 A420 Gr WPL6 A350 Gr LF2 A352 Gr LCB A320 Gr L7A194 Gr 7

A333 Gr 3 A420 Gr WPL3 A350 Gr LF3 A352 Gr LC3

AusteniticStainless

A312 Gr TP304 A403 Gr WP304 A182 Gr F304 A182 Gr F304 A193 Gr B8A194 Gr 8A312 Gr TP316 A403 Gr WP316 A182 Gr F316 A182 Gr F316



Steel

A312 Gr TP321 A403 Gr WP321 A182 Gr F321 A182 Gr F321

A312 Gr TP347 A403 Gr WP347 A182 Gr F347 A182 Gr F347MATERIALS ACCORDING TO ASTMPipes

A106 = This specification covers carbon steel pipe for high-temperature service. A335 = This specification covers seamless ferritic alloy-steel pipe for high-temperature

service. A333 = This specification covers wall seamless and welded carbon and alloy steel pipe

intended for use at low temperatures. A312 = Standard specification for seamless, straight-seam welded, and cold worked welded

austenitic stainless steel pipe intended for high-temperature and general corrosive service.Fittings

A234 = This specification covers wrought carbon steel and alloy steel fittings of seamless and welded construction.

A420 = Standard specification for piping fittings of wrought carbon steel and alloy steel for low-temperature service.

A403 = Standard specification for wrought austenitic stainless steel piping fittings.Flanges

A105 = This specification covers standards for forged carbon steel piping components, that is, flanges, fittings, valves, and similar parts, for use in pressure systems at ambient and higher-temperature service conditions.

A182 = This specification covers forged or rolled alloy and stainless steel pipe flanges, forged fittings, and valves and parts for high-temperature service.

A350 = This specification covers several grades of carbon and low alloy steel forged or ring-rolled flanges, forged fittings and valves for low-temperature service.

Valves A216 = This specification covers carbon steel castings for valves, flanges, fittings, or other

pressure-containing parts for high-temperature service and of quality suitable for assembly with other castings or wrought-steel parts by fusion welding.

A217 = This specification covers steel castings, martensitic stainless steel and alloys steel castings for valves, flanges, fittings, and other pressure-containing parts intended primarily for high-temperature and corrosive service.

A352 = This specification covers steel castings for valves, flanges, fittings, and other pressure-containing parts intended primarily for low-temperature service.

A182 = This specification covers forged or rolled alloy and stainless steel pipe flanges, forged fittings, and valves and parts for high-temperature service.

Bolds & Nuts A193 = This specification covers alloy and stainless steel bolting material for pressure vessels,

valves, flanges, and fittings for high temperature or high pressure service, or other special purpose applications.

A320 = Standard Specification for Alloy-Steel and Stainless Steel Bolting Materials for Low-Temperature Service.

A194 = Standard specification for nuts in many different material types.



FITTINGSA fitting is a connection between two pieces of pipe or fittings.Mechanical Joints are Flanges, Bolting, Gasket are Mechanical Joints

ELBOW

45 Elbow

A 45 degree elbow "long radius" (LR) has a centerline curvature equal to 1-1/2 times the nominal pipe size (NPS) for 3/4 inch and larger sizes.

A 45 degree elbow "long radius, long tangent" is a long radius (LR) with the centerline curvature equal to 1-1/2 times the nominal pipe size (NPS) and a straight extension at both ends (long tangent) for 2 inch and larger sizes. Tangent elbows provide a straight length at the end to accept a Slip-on Flange. The tangent end for the flange is not beveled.

A 45 degree elbow "three radius" is a long radius (LR) with the centerline curvature equal to 3 times the nominal pipe size (NPS).

90 Elbow

A 90 degree elbow "long radius" (LR) has a centerline curvature equal to 1-1/2 times the nominal pipe size (NPS) for 3/4 inch and larger sizes.

A 90 degree elbow "short radius" (SR) has a centerline curvature equal to 1 times the nominal pipe size (NPS) for 1 inch and larger sizes.

A 90 degree elbow "long radius, long tangent" is a long radius (LR) with the centerline curvature equal to 1-1/2 times the nominal pipe size (NPS) and a straight extension at both ends (long tangent) for 2 inch and larger sizes. Tangent elbows provide a straight length at the end to accept a Slip-on Flange. The tangent end for the flange is not beveled.

A 90 degree elbow "short radius, long tangent" is a short radius (SR) with the centerline curvature equal to 1 times the nominal pipe size (NPS) and a straight extension at both ends (long tangent) for 8 inch and larger sizes. Tangent elbows provide a straight length at the end to accept a Slip-on Flange. The tangent end for the flange is not beveled.

A 90 degree elbow "three radius" is a long radius (LR) with the centerline curvature equal to 3 times the nominal pipe size (NPS).

180 Return

A 180 degree return "long radius" (LR) has a centerline curvature equal to 1-1/2 times the nominal pipe size (NPS) for 3/4 inch and larger sizes.

A 180 degree return "short radius" (SR) has a centerline curvature equal to 1 times the nominal pipe size (NPS) for 1 inch and larger sizes.



TEE

Reducing Tee

Reducing tees have a single 90 degree branch from the main run of pipe. The branch is smaller than the main run.

Split Tee

Split Tee Horizontal Split Tee Vertical Split Tee with Cutout

Straight Tee

A straight tee has the same branch size as the pipe. These are used for making 90 degree branching from the main run of pipe.

Barred Tee

A barred tee is a tee used in pipelines that are pigged that has a restriction bar welded internally preventing the pig from traveling down a branch connection. The bars are installed so they are flush with the inside diameter of the pipeline to keep the pig from hanging up when it passes through.

REDUCER


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Concentric Reducer

The concentric reducer centerline of the inlet and outlet is at the same level.

Buttweld Datasheet - Concentric

Eccentric Reducer

The eccentric reducer offset is equals 1/2 times the larger ID minus the smaller ID.

The eccentric reducer is used to keep either the top or bottom of the pipe level. It is used with the flat side up FOT or flat side down FOB. In wet gas such as casing gas applications, an eccentric reducer should be used that is flat on bottom to prevent condensing liquids from pocketing.

It is common practice to install eccentric reducers on a liquid line that might have a little gas in it with the flat side of the reducer is put on the top. That ensures that any bubbles that come along the top pass immediately through the pump and not accumulate. If they accumulate, they may collect and enter the pump in bulk causing it to intermittently cavitate.

SWAGE

(SWG) There are three types - concentric, eccentric and ventury. A swage is used to connect buttwelded and screwed fittings/pipe to smaller or larger buttweld or screwed fittings/pipe.

"Concentric" swage centerline of the inlet and outlet is at the same level.

"Eccentric" swage is offset either on the top or bottom of the line level.

"Ventury" swage creates a smooth flow.

OLET

Branch connections are not just tee's and lateral's, they are also weldolets. Weldolets are buttweld branch connections that are designed to match or exceed the schedule of the pipe used. Each is marked with an outlet size and the pipe sizes that it can be welded to. If stamped 5-3x3/4" it will have an outlet size of 3/4" and fit pipe sizes 3", 3 1/2", 4", 5" and having a maximum gap between the pipe and olet of 1/32" for the largest size. Whatever your pipe size, an olet can be found to do the job. 4 inch and smaller are designed to fit numerous sizes of pipe, 5 inches and larger are designed for each specific size of pipe. A flat base is available for connecting to pipe caps and vessel heads.

Threaded Elbolet Threaded Elbolet Threaded Weldolet Weldolet Weldolet and Gate


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Valve

Threaded Socket Class 3000 - for use with Sch. 80 pipe.

Class 6000 - for use with Sch. 160 pipe. Class 3000 - for use with Sch. 80 pipe. Class 6000 - for use with Sch. 160 pipe.

Sockolet

(SOL) A sockolet is the same basic design as a "weldolet" or "threadolet". The difference is that a sockolet has a socket for welding versus the buttweld connection that a weldolet has. This makes a 90¬∞ branch and comes in full size or reducing for a straight piece of pipe. Sockolets are available in Class 3000, 6000 and 9000 for high pressures.

Threadolet

(TOL) A threadolet is the same basic design as a "weldolet" with the exception that a threadolet has a female threaded connection to mate with. This makes a 90¬∞ branch - comes in full size or reducing for a straight piece of pipe. Typically it is in the size range of 1/2" to 2" and is welded over a hole either drilled or burned in the pipe.

Weldolet

(WOL) This makes a 90¬∞ branch connection and - comes in full size or reducing for a straight piece of pipe. A weldolet is designated by the run length by the branch length. For example a 6-inch weldolet on a 10-inch pipe would be a 10x6 Weldolet. A weldolet is designed to minimize stress concentrations and provide integral reinforcement without the need for reinforcing the weld.

FLANGE

(FLG) A flange is a bolted connection where two pieces of pipe, equipment, fittings or valves can be connected together. They come in different styles, pressure ratings and sizes to meet the design requirements. The two most commonly used flange standards are ANSI/ASME B16.5 and BS 1560. The third is API Spec 6A which is for flanges used on wellhead and christmas tree equipment.

There are different types of flanges available for use. Depending on the service the line is being used for will dictate the flange material to be used. Referencing the proper specification will provide this information. This is why it is always important to have up to date P&ID's to help with the identification.

Flanges of different standards are not normally joined together. But if need be, seek engineering advise to ensure that the flanges are compatible.

There are six basic types of flanges:



Blind Flange - Lap Joint Flange - Slip On Flange - Socket Weld Flange - Threaded Flange - Welding Neck Flange

All these flanges have a raised flange face except the lap joint flange which has a flat flange face.

There are also a number of special flanges:

Orifice Flanges: Orifice Slip-On Flange - Orifice Socket Flange - Orifice Threaded Flange - Orifice Weld Neck Flange

Standard Connections: Long Weld Neck Flange - Heavy Barrel Flange - Full Barrel Flange

Ring Type Joint Flanges: RTJ Blind Flange - RTJ Slip-On Flange - RTJ Threaded Flange - RTJ Weld Neck Flange

Expander Flange

Reducing Flange

Studding Outlet: Flat Bottom Mount - Shell/Head Mount - Tangential Mount

Weldoflange / Nipoflange

Orifice Plate (part for orifice flange)

Spectacle Blind (part for flange)

GASKET

A gasket is a material that is used to seal the face of flanges, valves and equipment. Gaskets can be made from materials that are soft or hard, but will compress to make a tight seal. When compressed between two flange faces it will deform to match the surface grooves and irregularities. A gasket must be installed properly to prevent leakage. The surface of the flange must be clear of all foreign bodies such as dust, dirt or grease that could prevent a proper seal. To ensure a seal through out the life of the gasket, sufficient pressure or stress should be maintained to prevent leakage. It is very important to select the right gasket material to be used.

RING TYPE GASKET



SPIRAL WOUND GASKET

RING JOINT GASKET

ISOLATION GASKET

Isolation gaskets (Flange Insulating Kit) are used to stop the current flow across metallic pipelines by separating two flanges. The isolation of these pipeline segments allows cathodic protection for underground and above ground pipelines to control the stray electric current flow.

Isolation Gasket Type D

This gasket is designed to specifically fit into the groove of ring type joint flanges and come in both oval and octagonal shapes.


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Isolation Gasket Type E

A full face insulating gasket centers the gasket within the flange by the bolts. This gasket covers the whole face of the flange making it less likely of a short across the flanges by any foreign material.

Isolation Gasket Type F

A ring insulating gasket is centered within the bolts of the flange. This gasket only covers the face of the flange making easier the possibility of a short across the flanges by any foreign material.


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VALVE

The valve is a mechanism used to stop or open and regulate flow. The type of valve used depends on the application. In general, there are valves used for on-off (open-closed) applications, and throttling valves which can adjust flow. All valves fall into two basic types: stop valves and check valves.

CLASSIFICATION OF VALVESThe following are some of the commonly used valve classifications, based on mechanical motion:

Linear Motion Valves. The valves in which the closure member, as in gate, globe, diaphragm, pinch, and lift check valves, moves in a straight line to allow, stop, or throttle the flow.

Rotary Motion Valves. When the valve-closure member travels along an angular or circular path, as in butterfly, ball, plug, eccentric- and swing check valves, the valves are called rotary motion valves.

Quarter Turn Valves. Some rotary motion valves require approximately a quarter turn, 0 through 90°, motion of the stem to go to fully open from a fully closed position or vice versa.

Valve types Linear motion Rotary motion Quarter turn

Gate Valve x

Globe valve x

Plug valve x x

Ball valve x x

Butterfly valve x x

Swing check valve x

Diaphragm valve x

Pinch valve x


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Safety valve x

Relief valve x

Classification of valves based on motion

CLASS RATINGSPressure-temperature ratings of valves are designated by class numbers. ASME B16.34, Valves-Flanged, Threaded, and Welding End is one of the most widely used valve standards. It defines three types of classes: standard, special, and limited. ASME B16.34 covers Class 150, 300, 400, 600, 900, 1500, 2500, and 4500 valves.

Gate valve and check valve

Stop Valves: Stop valves are used to shut off or partially shut off the flow of liquids. Stop valves are divided into four basic types of valves: gate,globe, ball and butterfly.

Check Valves: Check valves are used to allow the flow of fluids in only one direction. There are four basic types: diaphragm check, lift check, swing check, and tilting-disk check.

BALL VALVE

(BV) A ball valve is a quarter turn valve used for changing the direction of a process stream (divert or shut off). Ball valves can be automated to automatically shutdown or open depending on the orientation of the actuator. True ball valves should not be used as control valves as velocities between the ball and seat can be high enough to wash out the sealing portion of the valve. The ball on the valve can be characterized to act as a control valve such as a V-ball type design.

Advantages & Disadvantages

Since the ball valve is a quarter turn valve, it is very easy to automate. Due to its widespread use, the ball valve is considered a commodity item and can be found at most piping supply shops.


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In large applications, a ball valve may be economically prohibitive. This is due to the amount of metal that makes up the body and ball. For large diameter applications that require a quarter turn valve, a butterfly valve may be appropriate.

Bore Size

The bore of a ball valve is the area through which the fluid flows. A full bore valve has an opening that is equal to the nominal pipe size (NPS) of the flowing pipe. A standard bore ball valve typically has an area that is equal to the NPS of the pipe one size smaller than the flowing line.

Full bore ball valves are the ideal solution where pressure drop is a concern. Full bore valves are the ideal choice where pigging of process lines is a major consideration. Normal "dumb" pigs may be able to deform across a reduced bore ball valve. Smart pigs, however cannot. Full port valves are normally used when inserting sample probes, injection quills or interface probes to facilitate removing the device from the system while under full line pressure.

Trunnion Ball Valves

Trunnion Design is simply the use of upper and lower supports to retain the ball under pressure. Named for the "trunnion" historically used to support a cannon, a ball valve trunnion essentially doubles the safety and usability of a ball valve. Another important benefit of the trunnion design is that it allows the Ball Valve to act as a true union: The downstream piping can be disconnected under full upstream pressure (user is responsible to ensure that downstream piping is drained of liquid and that valve is indeed closed and secured to upstream piping).

The trunnion on a two-way ball valve supports the ball in much the same way as the stem does at the top. The trunnion on a three-way ball valve is a much different design, being more like a supporting ring, but provides the exact same function and inherent stability.

Non-Trunion (Floating) Ball Valves

Floating ball valves are used in low pressure or small bore processes. A floating ball valve has two seats, located upstream and downstream of the ball. When the valve is closed, differential pressure across the valve assists in seating the ball.

GLOBE VALVE

(GLV) A globe valve is a type of valve used for regulating fluid flow, both on/off and throttling, it is a control valve. The name globe valve comes from the globular shape of the valve body. This valve is the most common control valve used and can be found in industries such as the oil and gas, chemical, pharmaceutical, shiping, pulp and paper.

Globe Valve Types:

Angle Globe Valve Cross Globe Valve



Straight Globe Valve

GATE VALVE

(GV) The gate valve is one of the most frequently used valve in piping systems and is classified as either "rising-stem" or "nonrising-stem" valves. The rising-stem gate valve has the stem attached to the gate, both gate and stem rise and lower together as the valve handwheel or actuator turns the stem. In the nonrising-stem gate valves the stem is threaded into the wedge, rising and lowering the wedge.

It is a multi turn valve which should be used for on and off service. If the valve is partially open as an attempt to throttle or control flow, turbulence from the stream could cause the wedge to vibrate and create a chattering noise. When fully opened, the gate valve creates minimal obstruction to the flow.

Gate valves control the process through the pipe with a gate. The gate might be wedge shaped or knife shaped, that slides up or down as the valve's handwheel is turned. As the handwheel is rotated, the gate slides through the valve body to block or release the flow.

ACTUATORS

An actuator is a device used to open, close, or control valves. The most commonly used types are electrical, hydraulic, and pneumatic. For high torque applications, electro-hydraulic actuators may be utilitzed. Actuators are mounted to the valves by a [wiki]linkage[/wiki]. Actuators may be quarter turn or multi-turn. They might fail in place, fail open or closed or continue to run, depending on the set up. Actuators are sized depending on their application. Butter fly valves, for example, require the highest torque immediately after opening and the torque requirements depend on the orientation of the valve.

Manual Actuators

Manual actuators are knobs, cranks, gear operators or hand levers. Movement may be quarter turn or multi-turn, depending on the required actuation.

Pneumatic Actuators

Pneumatic actuators use compressed air controlled by a separate solenoid valve, while motor actuators use an electric gear motor. Actuators may be used when valves are remotely located (such as on pipelines), located in hazardous areas, and when manual operation would be time consuming (like with large valves).

Pneumatic Actuators will typically have one of the following characteristics

Air to Open - An actuator installed in this configuration requires air to open. If the actuator is a rack and pinion actuator and is single acting, it must have a spring to force the valve closed when there is no air in the actuator. Air to open type actuators require air pressure and some known volume to open the valve. Actuators that require air to open are typically denoted as 'Fail Closed'



Air to Close - Air to Close is of a different configuration than the ATO type actuator described above. Air to Close means that constant pressure must be held on the acutator to keep the valve closed. If air pressure is lost the actuator will automatically open. Actuators that require air to close are typically denoted as 'Fail Open'

DOUBLE BLOCK AND BLEED

DOUBLE BLOCK AND BLEED SYSTEMSThe primary function of a double block and bleed system is for isolation and the secondary function is for intervention.Under certain conditions double block and bleed systems are needed to prevent product contamination or where it is necessary to remove essential equipment from service for cleaning or repairs while the unit continues in operation.Of course, such equipment must be provided with a spare or it must be possible to bypass it temporarily without shutting down the unit.The nature of the fluid, its pressure and temperature, and many other factors must be considered when determining the need for double block and bleed systems.

Generally, block valves should be considered for the onstream isolation of equipment if the fluid is flammable or otherwise hazardous, or if the fluid is in high-pressure or high-temperature service. Where double block valves are used, a NPS ¾ or larger bleed valve should be installed between the block valves.The purpose of the bleed valve is twofold. First, the bleed ensures that the upstream valve is in fact tight before slipping in a blind off the downstream block valve. The bleed connection also permits the safe withdrawal of moderate leakage from the upstream valve to again assure the tight shutoff of the downstream valve.Depending on the service conditions, it may be possible to use a single block valve with a body bleed to provide double block and bleed provisions for onstream isolation of equipment.Gate valves with flexible wedges and with body or bonnet bleed valve can serve this purpose if specifically tested in accordance with API-598 for double block and bleed quality valves.Some ball valves and nonlubricated plug valves, when equipped with a valve body bleed between the seats, can also be satisfactory substitutes for double block valves.Testing for double block and bleed quality valves requires the pressure-testing of each seat, with leakage measured through the valve body bleed as a means of substantiating the independent leak tightness of both the upstream and downstream seats of the valve.



DOUBLE BLOCK AND BLEED VALVESThe Double Block and Bleed Valve or a DBBV can perform the tasks of 3 separate valves (2 separate isolations and 1 drain valve) which apart from being hugely space saving can also save on weight and time due to installation and maintenance practices requiring much less work and the operator being able to locate and operate all 3 valves in one location.Double block and bleed valves operate on the principle that isolation can be achieved from both the upstream and downstream process flow / pressures.This is achieved by two ball, gate, globe, needle, etc. valves placed back to back, with a third "isolatable" valve in the centre cavity.Once isolation has been achieved in one or more of the main process isolation valves, the cavity that is created between these isolations can be drained. This is useful for flow diverting, sampling or injection situations, and for maintenance and or integrity check situations where seat leakage can be monitored through the third "bleed" valve.

The image on the left gives you a good impression, how a DBB valve is constructed.In this image example, three balls are mounted. 2 large balls that serve as a block (both are closed), and the small ball serve as the bleed (ball is in open position).

ISOLATION (STOP) VALVES IN PRESSURE RELIEF PIPINGThe article below (text) comes from the American Petroleum Institute (API)Sizing, Selection, and Installation of Pressure-Relieving Devices in Refineries, Part II-InstallationAPI recommended practice 520 fifth edition

Isolation (Stop) Valves in Pressure-Relief PipingIsolation block valves may be used for maintenance purposes to isolate a pressure-relief device from the equipment it protects or from its downstream disposal system. Since improper use of an isolation valve may render a pressure-relief device inoperative, the design, installation, and



administrative controls placed on these isolation block valves should be carefully evaluated to ensure that plant safety is not compromised. A pressure-relief device shall not be used as a block valve to provide positive isolation.

Inlet Isolation Valvesa. Valves shall be full bore. ASME Section VIII Appendix M recommends the use of full area isolation (stop) valves. Mandatory paragraph UG-135 (b)(1), of ASME Section VIII, requires that the opening through all pipe and fittings between a pressure vessel and its pressure-relief valve shall have the area of the pressure-relief device inlet. It is therefore recommended that the minimum flow area in the isolation valve be equal to or greater than the inlet area of the pressure-relief valve. The minimum flow area of the isolation valve and the inlet area of the pressurerelief valve can be obtained from the isolation valve manufacturer and the pressure-relief valve manufacturer.b. Valves shall be suitable for the line service classification.c. Valves shall have the capability of being locked or carsealed open.d. When gate valves are used, they should be installed with stems oriented horizontally or, if this is not feasible, the stem could be oriented downward to a maximum of 45° from the horizontal to keep the gate from falling off and blocking the flow.e. A bleed valve should be installed between the isolation valve and the pressure-relief device to enable the system to be safely depressurized prior to performing maintenance. This bleed valve can also be used to prevent pressure build-up between the pressure-relief device and the closed



outlet isolation valve.f. Consideration should be given to using an interlocking system between the inlet and outlet isolation valves to assist with proper sequencing.g. Consideration should be given to painting the isolation valve a special color or providing other identification. When placing the pressure-relief device into service, it is recommended to gradually open the isolation valve. This ramping up of system pressure can help prevent unwanted opening of a valve seat due to the momentum of the fluid. The inlet valve must be open fully.Outlet Isolation Valvesa. Valves shall be full bore. ASME Section VIII Appendix M recommends the use of full area isolation (stop) valves. To help minimize the built-up back pressure, it is recommended that the minimum flow area in the outlet isolation valve be equal to or greater than the outlet area of the pressure-relief valve. The minimum flow area of the outlet isolation valve and the outlet area of the pressure-relief valve can be obtained from the isolation valve manufacturer and the pressure-relief valve manufacturer respectively.b. Valves shall be suitable for line service classification.c. Valves shall have the capability of being locked or carsealed open. This outlet isolation shall never be closed while the vessel is in operation without using an inlet isolation valve that has first been closed with the space between the inlet isolation valve and the pressure-relief valve adequately depressured.d. A bleed valve should be installed between the outlet isolation valve and pressure-relief device to enable the system to be safely depressurized prior to performing maintenance. This bleed valve can also be used to prevent pressure build-up between the pressure-relief device and the closed outlet isolation valve.e. Consideration should be given to using an interlocking system between the inlet and outlet isolation valves to assist with proper sequencing.f. Consideration should be given to painting the isolation valve a special color or providing other identification. When the outlet isolation valve is used in conjunction with an inlet isolation valve, upon commissioning the pressurerelief device, the outlet isolation valve shall be opened fully prior to the inlet isolation valves.

EXPANSION JOINTS & PIPING EQUIPMENT

WHAT ARE EXPANSION JOINTS'SExpansion joints are used in piping systems to absorb thermal expansion or terminal movement where the use of expansion loops is undesirable or impractical. Expansion joints are available in many different shapes and materials.Below you will find a short description of Metallic, Rubber and Teflon® joints.

METALLIC EXPANSION JOINTS (BELLOWS)Metallic Expansion Joints are installed in pipe work and duct systems to prevent damage caused by thermal growth, vibration, pressure thrust and other mechanical forces.There is a wide range of metallic bellows designs in a variety of materials. Options range from



the simplest convoluted bellows used in petroleum refineries.Materials include all types of stainless steels and high grade nickel alloy steels.Any pipe connecting two points is subjected to numerous types of action which result in stresses on the pipe. Some of the causes of these stresses are:

internal or external pressure at working temperature weight of the pipe it self and the parts supported on it movement imposed on pipe sections by external restraints thermal expansion

RUBBER EXPANSION JOINTSRubber Expansion Joints are a flexible connector fabricated from natural or synthetic elastomers and fabrics with metallic reinforcements designed to provide stress relief in piping systems due to thermal changes.When flexibility for this movement cannot be designed into the piping system itself, an expansion joint is the ideal solution. Rubber expansion joints compensate for lateral, torsional and angular movements preventing damage and undue downtime of plant operations.The special construction of the rubber joints can solve problems like:

Vibration, Noise, Shock, Corrosion, Abrasion Stresses, Load Stress, Equipment Movement Vibration, Pressure Pulsation and Movement in a Piping System



INTRODUCTION TO PIPE RACKS and PIPE SUPPORTS

PIPE SUPPORTSPipe is held either from above by hangers or supports of various types on which it rests. Hangers are also referred to as supports.There are a number of typical pipe supports that can be installed to support dead weight loads, and restrain the pipe for thermal and dynamic loads.The designs are only limited by the imagination of the engineer and designer, as literally thousands of different designs have been used for special purposes.Pipe is rested on or secured to a support member usually of a standard structural shape (I-beam, wide flange beam, angle, channel etc.). The pipe may be secured to this member with a pipe support.Pipe supports and hangers are devices which transfer the loads from the pipe or the structural attachment to the supporting structure or equipment. They include rod hangers, spring hangers,



sway braces, turnbuckles, struts, anchors, saddles, rollers, brackets, and sliding supports. Structural attachments are elements that are welded, bolted, or clamped to the pipe, such as clips, lugs, clamps, clevises, and stops.The correct and economical selection of the supports for any piping system usually presents difficulties of varying degrees, some relatively minor and others of a more critical nature. Proper support selection should be the objective of all phases of design and construction.

PIPE SUPPORTS STANDARDSThe code ASME B 31.3 specifies under clause 321.1.1 the ayout and design of piping and its supporting elements shall be directed toward preventing the following:

Piping stresses in excess of those permitted in the Code Leakage at joints Excessive thrusts and moments on connected equipment (such as pumps and turbines) Excessive stresses in the supporting (or restraining) elements Resonance with imposed or fluid-induced vibrations Excessive interference with thermal expansion and contraction in piping which is otherwise

adequately flexible Unintentional disengagement of piping from its supports Excessive piping sag in piping requiring drainage slope Excessive distortion or sag of piping (e.g., thermoplastics) subject to creep under conditions of

repeated thermal cycling Excessive heat flow, exposing supporting elements to temperature extremes outside their

design limitsOther support standards

ASME 31.1 & 31.3 ie Power Piping & Process Piping MSS SP-58 Pipe Hangers and Supports - Materials, Design, and Manufacture MSS SP-69 ANSI/MSS Edition Pipe Hangers and Supports - Selection and Application MSS SP-77 Guidelines for Pipe Support Contractual Relationships MSS SP-89 Pipe Hangers and Supports -Fabrication and Installation Practices MSS SP-90 Guidelines on Terminology for Pipe Hangers and Supports

DETERMINATION OF SUPPORT LOCATIONSSupport locations are dependent on many considerations, such as pipe size, piping configuration, the location of heavy valves and fittings, and the structure that is available for support.Following rules of thumb will help when doing the flexibility analysis and operation and maintenance:

As much as possible, attach supports to straight pipe rather than elbows, other fittings, valves, flanges or instruments, but provide supports near instruments, and other devices that are likely to be removed for maintenance.

Provide space for adding loops to piping near load sensitive equipment, e.g. in pump suction lines.

Consider the need to add friction reducing slides between the piping and support steel. Support piping such that spools to be removed for equipment maintenace can be removed

without adding temporary supports. Minimize the use of spring hangers.



DETERMINATION OF LOADS AND MOVEMENTSThe anticipated movement at each support point dictates the basic type of support required. Each type of support selected must be capable of accommodating movements.It is a good practice to select first the most simple or basic rigid support type and to add to the complexity only as conditions warrant. No advantage will be realized in upgrading a support when a simpler, more economical type can be shown to satisfy all the design requirements.Both vertical and horizontal movement must be evaluated. When piping vertical movement is small, the use of simple rod hangers should be adequate. With small vertical movement and significant horizontal movement, the simple rod hanger will still suffice, provided the overall length is sufficient to keep the angular swing of the rod within reasonable limits-normally accepted as being 4° from the vertical.When one is calculating the total movement experienced by the support, both horizontal displacements and the vertical displacement must be combined and normalized to the axis of the support. Consideration should be given to relocating the upper connection some percentage (usually two-thirds) of the total movement as a means for reducing the angularity in the hot position.For piping supported from below, some form of slide must be incorporated to provide for the horizontal movement; or, in the case of ensured longitudinal movement, a pipe roll may be used. Rollers are usually only used on long runs of piping supported on racks such as found in refinery piping.Suspended hangers with considerable horizontal movement and low headroom will require either single- or doubledirection trolleys or rollers. Where both longitudinal and lateral movements are large, consideration may be given to the use of a single-direction trolley oriented on the resultant movement vector.

OFTEN USED PIPE SUPPORTSAnchorsA rigid support that restricts movement in all three orthogonal directions and all three rotational directions. This usually is a welded stanchion that is welded or bolted to steel or concrete.Two types of anchors exist: fixed and directional.Fixed anchors are used in locations where all movement of a line must be prevented. In piping terms this is called a fixed point. The most common way to anchor a pipe is to weld the pipe directly to a support or structural member. If the pipe to be anchored is insulated, first a pipe shoe is welded to the pipe and then the shoe is welded to the steel structure.Directional anchors are used to force movement to occur in one direction while preventing it from occuring in the opposite direction. Directional anchors are used to direct a pipe's movement away from buildings, structures, equipment etc..

Dummy Leg SupportsA dummy leg is an extension piece welded to an elbow in order to support a pipe line, and rests or anchors on some steel member.Pipe size, length and wall thickness of the pipe-extension depends on several factors such as the total load, the parent pipe line size etc..



Hanger RodsA vertical pipe support that incorporates a rod. It may be a rigid, variable spring or constant support hanger. Hanger is a term that often means quite different things to different people.Rod hangers or pipe hangers attaches to the pipe by a U bolt, a clevis, a pipe clamp etc. to structural steel above.The rod hanger provides support in the vertical direction and allows limited motion in the horizontal direction. Adjustment in the vertical direction can be accomplished by threads or a turnbuckle.

GuidesWhen total restriction of pipe movement is not required, pipe guides are used.Pipe guides confine movement along the pipe's lineal ax



Constant Load HangerA specially engineered hanger that is designed to travel through many inches of vertical travel with a minimal change in support load. There are different styles and types depending on the manufacturers. Per MSS SP-58 a constant support hanger can be within specification and still have a load variation of plus minus 6% through the travel range.Some suppliers claim a tighter tolerance on the load variation.Constant hangers and constant supports are used for piping and related components where higher levels of vertical travel occur. Their job is to transfer the working load over the whole travel area while maintaining constancy, i.e., without any considerable deviations. The functional precision of the constant hanger is decisive for the favorable long term behaviour of the components concerned.Constant hangers compensate for vertical movement caused by thermal expansion. Via constant hangers, the respective piping loads are constantly absorbed and transferred with no significant deviation over the whole range of movement.

SUMMARY OF PIPE SUPPORTSPipe supports come in many configurations, and are designed to constrain pipe motion in one, two, or three space coordinates. Only the most common types are described on this page. Manufactures have catalogs that thoroughly illustrate supports of all types.

STANDARD PARTS OF PIPE SUPPORTS



Steel clevisA device which provides for the attachment of a threaded rod to a

bolted or pinned connection.Clevises are some of the most

frequently used linking elements in industry. These parts can be

found everywhere where simple movements are required, e.g.

linear pulling, pushing or even axle offset compensation.

In addition to standard clevises made of steel, there are also

clevises made of stainless steel.

Steel turnbuckleA turnbuckle, stretching screw or bottlescrew is a device for

adjusting the tension or length of ropes, cables, tie rods, and other

tensioning systems.It normally consists of two

threaded eyelets, one screwed into each end of a small metal

loop, one with a left-hand thread and the other with a right-hand

thread. The tension can be adjusted by rotating the loop,

which causes both eyelets to be screwed in or out

simultaneously, without twisting the eyelets or attached cables.

Pipe ClampA pipe attachment for

suspension of horizontal stationary insulated lines.One of the most common

clamps in the petro and chemical industry.



Double Bolt Pipe ClampA pipe attachment for

suspension of horizontal stationary lines.

Recommended for the suspension of pipe requiring up

to NPS 4 of insulation and where flexibility of the clamp

may be necessary.

Extension pipe or riser clampA Riser clamp is a device used

for suspension of vertcal stationary lines without the use

of hanger rods and by mechanical building trades to

support vertical runs of piping at each floor level.

The devices are placed around the pipe and integral fasteners

are then tightened to clamp them onto the pipe.

The friction between the pipe and riser transfers the weight of the pipe through the riser to the

building structure.Risers are generally located at floor penetrations, particularly for continuous floor slabs such

as concrete.



Round Bend U-BoltA U-shaped rod with threaded

ends used as a support or guide.U-bolts come in all sizes and shapes, but, there are many

common features. In the manufacture of millions of these

items, there is a common nomenclature that appears throughout the industry for many of the dimensional

characteristics.

Adjustable steel band hangerA pipe attachment for

suspension of horizontal stationary lines and providing a means for vertical adjustment.Function: For fire sprinkler and other general light weight piping

purposes.

Welded attachmentA structural attachment welded to the bottom of structural steel members and used as a means

for connecting hanger rods etc..



Plate LugA structural attachment which

provides a means of connecting rodtype hangers to structural

steel members via a pin or bolt through the hole of the lug.

Adjustable pipe supportThis support type is used for support of piping from below

without welding to the pipe and consists of a steel saddle, nipple, and pipe reducer, and it connects

to a threaded pipe standard.

NPSWater

Service

Steam, Gas

Air Service

GENERAL NOTES:

Suggested maximum spacing between pipe supports for horizontal straight runs of standard and heavier pipe at maximum operating temperature of 750°F (400°C)Does not apply where span calculations are made or where there are concentrated loads between supports, such as flanges, valves, specialties, etc.The spacing is based on a fixed beam support with a bending

1 2.1 2.7

2 3.0 4.0

3 3.7 4.6

4 4.3 5.2

6 5.2 6.4



stress not exceeding 2,300 psi (15.86 MPa) and insulated pipe filled with water or the equivalent weight of steel pipe for steam, gas, or air service, and the pitch of the line is such that a sag of 0.1 in. (2.5 mm) between supports is permissible.

8 5.8 7.3

12 7.0 9.1

16 8.2 10.7

20 9.1 11.9

24 9.8 12.8

SUPPORT LOCATIONSThe locations of piping supports are dependent upon four factors: pipe size, piping configuration, locations of valves and fittings, and the structure available for support. Individual piping materials have independent considerations for span and placement of supports.Pipe size relates to the maximum allowable span between pipe supports. Span is a function of the weight that the supports must carry. As pipe size increases, the weight of the pipe also increases. The amount of fluid which the pipe can carry increases as well, thereby increasing the weight per unit length of pipe.The configuration of the piping system affects the location of pipe supports. Where practical, a support should be located adjacent to directional changes of piping. Otherwise, common practice is to design the length of piping between supports equal to, or less than, 75% of the maximum span length where changes in direction occur between supports. Refer to the appropriate piping material chapters for maximum span lengths.Valves require independent support, as well as meters and other miscellaneous fittings. These items contribute concentrated loads to the piping system. Independent supports are provided at each side of the concentrated load.Location, as well as selection, of pipe supports is dependent upon the available structure to which the support may be attached. The mounting point shall be able to accommodate the load from the support. Supports are not located where they will interfere with other design considerations. Some piping materials require that they are not supported in areas that will expose the piping material to excessive ambient temperatures. Also, piping is not rigidly anchored to surfaces that transmit vibrations. In this case, pipe supports isolate the piping system from vibration that could compromise the structural integrity of the system.Spacing is a function of the size of the pipe, the fluid conveyed by piping system, the temperature of the fluid and the ambient temperature of the surrounding area. Determination of maximum allowable spacing, or span between supports, is based on the maximum amount that the pipeline may deflect due to load. Typically, a deflection of 2.5 mm is allowed, provided that the maximum pipe stress is limited to 1,500 psi or allowable design stress divided by a safety factor of 415, whichever is less. Some piping system manufacturers and support system manufacturers have information for their products that present recommended spans in tables or charts. These data are typically empirical and are based upon field experience.

PIPE SPAN CHARTSPipe Span Charts are very nice, but not more than a guide. I've seen several tables and charts, all with different values.



You should consider the material used, wall thickness, density of the medium, isolation, etc..For really good assessment of working stresses and deflections, pipe stress calculations are needed. Also, the engineer must be determine what kind of support he wants to use. Should there be limits to the movements, or even a fixed point etc. etc..Supporting is a profession.


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