PNE00001

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COMPLETE REVISIONFebruary 2002

Process Industry PracticesPiping

PIP PNE00001Design of ASME B31.3 Metallic Piping Systems

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PURPOSE AND USE OF PROCESS INDUSTRY PRACTICES

In an effort to minimize the cost of process industry facilities, this Practice has been prepared from the technical requirements in the existing standards of majorindustrial users, contractors, or standards organizations. By harmonizing these technicalrequirements into a single set of Practices, administrative, application, and engineeringcosts to both the purchaser and the manufacturer should be reduced. While this Practiceis expected to incorporate the majority of requirements of most users, individualapplications may involve requirements that will be appended to and take precedenceover this Practice. Determinations concerning fitness for purpose and particular mattersor application of the Practice to particular project or engineering situations should not

be made solely on information contained in these materials. The use of trade namesfrom time to time should not be viewed as an expression of preference but ratherrecognized as normal usage in the trade. Other brands having the same specificationsare equally correct and may be substituted for those named. All Practices or guidelinesare intended to be consistent with applicable laws and regulations including OSHArequirements. To the extent these Practices or guidelines should conflict with OSHA orother applicable laws or regulations, such laws or regulations must be followed.Consult an appropriate professional before applying or acting on any materialcontained in or suggested by the Practice.

This Practice is subject to revision at any time by the responsible Function Teamand will be reviewed every 5 years. This Practice will be revised, reaffirmed, or

withdrawn. Information on whether this Practice has been revised may be found atwww.pip.org.

Process Industry Practices (PIP), Construction Industry Institute, TheUniversity of Texas at Austin, 3925 West Braker Lane (R4500), Austin,Texas 78759. PIP member companies and subscribers may copy this Practicefor their internal use. Changes, overlays, addenda, or modifications of anykind are not permitted within any PIP Practice without the express writtenauthorization of PIP.

PIP will not consider requests for interpretations (inquiries) for this Practice.PRINTING HISTORY

November 1996 Issued February 2002 Complete Revision

Not printed with State funds

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COMPLETE REVISION February 2002

Process Industry PracticesPiping

PIP PNE00001Design of ASME B31.3 Metallic Piping Systems

Table of Contents

1. Introduction..................................31.1 Purpose ............................................. 31.2 Scope................................................. 3

2. References....................................32.1 Process Industry Practices................32.2 Industry Codes and Standards.......... 42.3 Government Regulations................... 4

3. Definitions ....................................5

4. General .........................................5

5. Design Conditions ....................... 55.1 Design Pressures

and Temperatures .............................5

6. Design Practices ..........................66.1 Basic Layout ......................................66.2 Piping................................................. 76.3 Isolation (Block) Valves ..................... 86.4 Control Valve Manifolds..................... 8

6.5 Vents, Drains, and Sample Outlets ... 96.6 Check Valves................................... 106.7 Blanks (Blinds)................................. 106.8 Strainers and Filters ........................ 116.9 Utility Piping Connections to

Process Equipment ......................... 11

7. Hot Tapping................................ 128. Piping Components................... 12

8.1 General............................................ 128.2 Pipe.................................................. 138.3 Joints and Fittings............................ 138.4 Branch Connections ........................ 148.5 Valves.............................................. 148.6 Flanges............................................ 168.7 Gaskets ........................................... 178.8 Bolting.............................................. 17

9. Piping Flexibility........................ 17

10. Piping Support......................... 17

Process Industry Practices Page 1 of 21

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PIP PNE00001 COMPLETE REVISION Design of ASME B31.3 Metallic Piping Systems February 2002

11. Specific Piping Systems..........1711.1 Instrument Air...................................1711.2 Plant Air............................................1811.3 Cooling Water ..................................1811.4 Utility Water......................................1811.5 Potable Water ..................................1811.6 Steam and Steam Condensate

Removal ...........................................1811.7 Utility Stations ..................................1911.8 Burner Fuel Piping ...........................2011.9 Heat Transfer Fluid Piping ...............21

12. Fabrication, Assembly, andErection .....................................21

Page 2 of 21 Process Industry Practices

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PIP Piping Material Specifications Line Classes

2.2 Industry Codes and Standards

American Petroleum Institute (API)

API 570 Piping Inspection Code: Inspection, Repair, Alteration, and Rerating of In-Service Piping Systems

API 602 Compact Steel Valves

API 614 Lubrication, Shaft-Sealing, and Control-Oil Systems for Special- Purpose Applications

API 650 Welded Steel Tanks for Oil Storage

API 2201 Procedures for Welding or Tapping on Equipment in Service

American Society of Mechanical Engineers (ASME)

ASME Boiler and Pressure Vessel Code

Section VIII Pressure Vessels, Division 1 ASME B16.5 Pipe Flanges and Flanged Fittings

ASME B16.25 Buttwelding Ends

ASME B16.36 Orifice Flanges

ASME B16.47 Larger Diameter Steel Flanges: NPS 26 through NPS 60

ASME B16.48 Steel Line Blanks

ASME B31.3 Process Piping

ASME B36.10M Welded and Seamless Wrought Steel Pipe

ASME B36.19M Stainless Steel Pipe

Crane Technical Publication Crane Technical Publication 410 Flow of Fluids

National Electrical Manufacturers Association (NEMA)

NEMA SM-23 Steam Turbines for Mechanical Drive Service

Manufacturers Standardization Society (MSS)

MSS SP-6 Standard Finishes for Contact Faces of Pipe Flanges andConnecting-End Flanges of Valves and Fittings

2.3 Government Regulations

U.S. Department of Labor, Occupational Safety and Health Administration(OSHA)

OSHA 29 CFR 1910.147 Control of Hazardous Energy Sources(Lockout/Tagout)


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COMPLETE REVISION PIP PNE00001February 2002 Design of ASME B31.3 Metallic Piping Systems

3. Definitions

As used in this Practice:

dead leg : A pipe section connected to a flowing stream where the pipe section is not self-draining and is not normally flowing

IREB: Integrally reinforced extended body

operating : As applied to vents and drains, being used regularly when the source equipment or piping is in service and/or pressurized

P&ID : Piping and Instrumentation Design

shall : Specification requirement unless otherwise authorized by the owner

should : Recommended good practice, not a requirement

SMYS : Specified minimum yield strength

4. General

4.1 Piping systems shall comply with this Practice and with all applicable federal, state,and local laws.

4.2 New piping systems within the scope of this Practice shall conform to the Code .

4.3 Alterations to existing piping systems shall comply with API 570 . Changes in serviceor in design conditions are considered alterations.

4.4 Items that are normally fabricated from piping components (e.g., strainers anddevices that serve such purposes as mixing, separating, snubbing, distributing, andmetering or controlling flow), if identified by the owner as specialty piping (SP)items, shall be designed in accordance with this Practice unless otherwise specified

by the owner.

4.5 Design of piping at machinery shall be in accordance with PIP REIE686 and NEMA SM-23, as applicable.

4.6 All piping shall be identified by the owner as either Category D, Category M, high pressure, or normal fluid services as defined in ASME B31.3 . Severe cyclicconditions per ASME B31.3 shall also be identified.

5. Design Conditions

5.1 Design Pressures and Temperatures

5.1.1 The internal and external design pressure and temperature of piping shall bedetermined by considering the following conditions:

a. Normal operations


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b. Start-up operations, including any start-up procedure, operation,routing, etc.

c. Shutdown operations, including shutdown procedures, operations, pumpout, etc.

d. Switching operations, including any cyclic regeneration, spare pumpswitching, coke drum switching, etc.

e. Regeneration procedures

f. Equipment bypassing

g. Turndown operations

h. Pump shutoff (deadhead) pressure

i. Any control valve in a fully opened or closed position

j. Any block valve in a fully opened or closed position, except for lockedor car-sealed valves

k. Blocked exits

l. Equipment trip or shutdown

m. Upset conditions

n. Maintenance, repair, or neutralization procedures

o. On-stream or purging operations

p. Steamout or purging operations

q. Solar temperature effects

r. Heat-tracing effects

5.1.2 The design minimum temperature shall be determined by considering thefollowing:

a. Normal conditions

b. Expected autorefrigeration effects, including emergency depressuring

Note: The design minimum temperature shall be the coincidentaltemperature when the pressure reaches 25% of the design

pressure.

c. One-day-mean low temperature per API 650 , Figure 2-2

6. Design Practices

6.1 Basic Layout

Piping layout shall be in accordance with PIP PNC00003 .


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6.2 Piping

6.2.1 General

6.2.1.1 Piping should be located above grade. Exceptions include firewatersupply systems, cased road and tank dike crossings, lines in concretetrenches, oil-free compressed air lines, lines with secondarycontainment and a leak-detection method, and other lines asdesignated by the owner. All below-grade piping, including piping intrenches, shall be protected from external corrosion. Buried steel

piping in hazardous materials service shall be externally coated andcathodically protected. The minimum cover over buried process

piping shall be 18 inches (46 cm) in paved or unpaved areas and30 inches (76 cm) under paved roads except under a reinforcedconcrete slab or other protective cover approved by the owner.Sewers may be covered by this Practice if specified by the owner.

6.2.1.2 When a block valve bypass is required, it shall be shown on the

applicable Piping & Instrument Diagrams (P&ID). Bypasses shall beintegral with the valve or installed in the piping immediatelyadjacent to the valve.

6.2.1.3 Piping layouts in all services shall be designed to eliminate the presence of dead legs. Where dead legs cannot be avoided, utilizeeither corrosion resistant materials or an approved coating system forthe dead leg section. Live dummy legs are not permitted.

6.2.1.4 In locations where potentially severe vibration can occur, small piping branches (i.e., NPS 2 and smaller) shall be adequatelydesigned to minimize its effects. The following examples areacceptable practices/configurations, depending on the severity of the

vibration:a) Brace all nipples (with reinforcing pads if required).

b) Where bracing cannot be effectively provided, installschedule 160 nipples with reinforcing pads.

c) Use an API 602 IREB valve.

d) Brace all configurations that have a nipple between thewelding boss and the root valve.

6.2.1.5 Blind flanges shall be used as end closures on flanged ends andvalves, unless end caps are clearly indicated by design necessity.

6.2.1.6 Flanged connections with long exposed bolts for sandwichedcomponents, e.g., wafer type valves, should not be used in firehazardous areas unless the bolting is protected by a fire-resistantshield. This recommendation does not apply to standard spectacle

plates and blinds.

6.2.1.7 Jackscrews shall be used to facilitate flange separation formaintenance. Joint assemblies that often require frequent separationinclude orifice plates, spectacle plates, spacers, screens, and dropout


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spools. Piping layout shall be designed such that flanges can beseparated without excessive force. Jackscrews shall be accessiblefrom both sides of the pipe. For orifice flanges, jackscrews shall beinstalled at three- and nine-oclock positions. When flange separatorsare used, jackscrews are not required.

6.3 Isolation (Block) Valves

6.3.1 Block valves shall be provided at vessel and storage tank nozzles as follows:

a. In piping at all nozzles below the maximum operating liquid level ofstorage tanks

b. In liquid draw-off lines of vessels containing 10,000 pounds (4,550 kg)or more of a flammable liquid at the maximum operating liquid levelwhen the line does not contain a block valve located within 30 feet(9 m) in a horizontal direction from the vessel

6.3.2 Block valves shall be provided for piping crossing the plant limits andoperating unit limits as required for the planned operation, isolation, andmaintenance of the plant as directed by the owner.

6.3.3 Where positive isolation is required or cross-contamination cannot betolerated, one of the following shall be used:

a. Blanks

b. Two block valves with a bleeder valve between them

c. A double-seated valve (e.g., expanding gate or plug, trunnion-mounted ball, through conduit slab gate, etc.) and with body bleeder

d. Removable spool

6.3.4 Valving of operating vent, drain, and sample connections shall have one block valve as a minimum. Additional block valves shall be per ownerrequirements.

6.3.5 Equipment that may be removed from service during unit operation shall befurnished with single block valves with provisions for blinding or blanking.

6.3.6 In all process services, branches sized NPS 2 and smaller shall have a rootvalve located as close as feasible to the run. The root valve shall be no fartherthan three times the branch diameter (except for insulated lines) measuredfrom the far end of the boss to the near end of the valve. Unions shall not beinstalled in the pipe section between the main pipe run and the root valve.

6.3.7 Flangeless valves shall not be used as the first block valve against storagetanks or vessels containing hydrocarbons or hazardous materials.

6.3.8 Crane Technical Publication 410 provides information on sizing valves.

6.4 Control Valve Manifolds

6.4.1 When specified, control valves shall be installed with a valved bypass and a block valve on each side of the control valve. As a minimum, block and


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bypass valves shall be provided in the control valve manifold for thefollowing cases:

a. Control valves where loss of control function would adversely affect plant operations as determined by the owner

b. Services where shutdown cannot be tolerated (e.g., fuel lines to furnacesor boilers, steam reducing stations [main headers], etc.)

c. Services in which the absence of blocks and bypass valves wouldinhibit start-up efforts as determined by the owner

6.4.2 Bleed valves shall be provided for each control valve manifold. One bleedvalve shall be located between the upstream block valve and the controlvalve. An additional bleed valve on the downstream side of the control valveshall be provided when specified.

6.5 Vents, Drains, and Sample Outlets

6.5.1 Valved vent and drain connections shall be furnished on all equipment that isnot self-venting or self-draining. Connections shall be located on equipment,if practical, but may be located in connecting piping when there are no

blocks between the vent or drain connections and the equipment.

6.5.2 Vent connections shall be furnished for trapped high points of piping andshall be one of the following:

a. Valved when required for operational purposes or removal of processfluid

b. Plugged, valve omitted, for hydrostatic test purposes

6.5.3 Drain connections shall be furnished for the low points of all lines locatedabove grade and shall be one of the following:

a. Valved when required for operational purposes or removal of processfluid

b. Plugged, valve omitted, for hydrostatic test purposes

6.5.4 Vent, drain, and sample outlet connections shall be NPS 3/4 minimum size,unless otherwise specified. All connections from piping in services involvingfluids with suspended solids or materials that are of high viscosity shall be

NPS 1 minimum size.

6.5.5 Operational vent and drain connections shall be designed to drain liquid fromequipment and piping in 2 hours or less, unless otherwise specified.

6.5.6 Hydrocarbon vapors or mixtures of hydrocarbon vapors and other vapors(e.g., steam) may be discharged to the atmosphere contingent on adequatesafety and environmental considerations.

6.5.7 All vents and drains open to the atmosphere shall be provided with plugs or blind flanges.

6.5.8 Cooling shall be considered for sample outlets in piping or equipmentoperating at 140 F (60 C) or higher. One cooler may be used for multiplesample outlets.


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6.5.9 For horizontal piping, the sample connection shall be located at the side ofthe pipe for liquids and at the top of the pipe for gases, unless otherwisespecified.

6.5.10 Discharge from drains emptying into open hubs (e.g., drain cups or sumps)

shall be visible from the location of the drain valve when practical.6.5.11 Operating vents and drain lines shall discharge into a closed system when

releasing controlled materials, as defined by the owner.

6.6 Check Valves

6.6.1 Check valves shall be installed in the discharge piping of centrifugal pumps,unless otherwise specified.

6.6.2 Check valves shall be used where utility or chemical injection lines are permanently tied into process lines or equipment.

6.6.3 In no case shall a check valve serve as a substitute for a block valve for flow

isolation purposes.6.6.4 Check valves in vertical piping shall be installed for upward flow only and

shall be installed with a drain connection immediately above the check valve.

6.6.5 When a lower pressure rated system flows into a higher pressure ratedsystem, a check valve shall be installed in the lower pressure connection andthe higher pressure rating shall extend to include the check valve.

6.6.6 A check valve in the higher pressure system should be considered where asudden loss of pressure in the higher pressure system could lead toundesirable contamination from the lower pressure system.

6.6.7 For all sizes NPS 3 and above, a turbulence-free minimum distance of five pipe diameters upstream and two pipe diameters downstream of every checkvalve should be maintained. No pipefittings (e.g., elbows, reducers, tees, etc.)or flow-restricting devices (e.g., orifices, control valves, etc.) should beinstalled in these zones. Valves in intermittent service and valves in skid-mounted systems are exempt from these requirements.

6.6.8 Crane Technical Publication 410 provides information on sizing checkvalves.

6.7 Blanks (Blinds)

6.7.1 The piping layout should provide for the insertion of line blanks for flangedequipment isolation for maintenance, inspection, testing, and alternativeoperation. If piping flexibility and equipment arrangement do not permit theinsertion of temporary maintenance blanks at convenient flanges, permanentline blanks shall be provided as follows:

a. At piping connections at equipment that can be physically entered

b. At plant limits in process, utility, and auxiliary (e.g., fuel oil, fuel gas) piping connected to other piping outside plant limits that may be in useduring shutdown of the plant


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6.7.2 Figure-8 type blinds shall not exceed 100 pounds (45 kg) or NPS 12.Figure-8 type blinds within these limits are shown in the following table:

Class Max. Figure-8Size (NPS)

150 and 300 12600 and 900 8

1500 and 2500 6

6.7.3 Circular blanks or spacers shall be used for sizes exceeding the limits ofSection 6.7.2.

6.7.4 Circular blanks or spacers shall be used in place of figure-8 type blinds forcold-insulated piping below 70 F (21 C).

6.7.5 Commercially available blinding systems acceptable to the Code are permitted.

6.7.6 Guidance for blanks is available in ASME B16.48.

6.8 Strainers and Filters

6.8.1 When strainers are not furnished as part of the equipment, strainers in the piping shall be considered for the protection of the following equipment:

a. Mechanical equipment per PIP REIE686

b. Steam traps and steam jet ejectors in steam inlet lines

c. Burners in main fuel oil supply piping

d. Upstream of low noise design control valves

6.8.2 When filters are not furnished as part of the equipment, filters shall be provided in the piping for the protection of the following equipment:

a. Pneumatically actuated equipment in air supply piping

b. In the air piping, upstream of air dryers

c. Open-air intakes for blowers, compressors, or engines

6.8.3 Providing permanent strainers with plugged connections for the installationof differential pressure measurement across the strainer shall be considered.

6.8.4 Installation of spacer rings may be required after temporary strainers areremoved.

6.9 Utility Piping Connections to Process Equipment

6.9.1 Firewater systems shall not be connected to process equipment except via atemporary connection when the equipment is not in operation and not under

pressure.

6.9.2 No permanent connections other than air or steam shall be made to processequipment operating above 212F (100C) nor shall water or steam be

permanently connected to equipment that operate below 32F (0C).


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6.9.3 Permanent connections without a break tank shall not be made except whenthe required service is continuous or frequent (at least twice per week) or isneeded for emergencies.

6.9.4 When air is injected as a reaction agent, the control shall be such that the

hydrocarbon/air mixtures shall not enter the flammable range unless required by the process. Instrumentation shall be provided to shut off the airflow if the process flow fails. In addition, a restriction orifice shall be provided.

6.9.5 For all components of permanent connections, the pressure/temperaturerating shall be suitable for either the process or the utility service, whicheveris more severe.

6.9.6 For temporary connections, the pressure/temperature rating of the processside shall extend to the hose or breakaway spool.

6.9.7 If the process fluid requires internal lining or material other than that used inthe utility system, the lining or the material shall extend from and include thecheck valve on the process side. Valves with bodies of gray cast iron, ductileiron, or low melting point alloys (e.g., brass or bronze) shall not be used in a

permanent connection including the utility side. The material selection of thevalve bodies and trim in a permanent connection shall be suitable for both the

process and the utility fluid.

6.9.8 Operator access shall be provided to the block valves on either side and tothe blind or breakaway spool of the connection. Chain-operated valves shallnot be used.

7. Hot Tapping

Hot tapping shall be in accordance with API 2201 and OSHA 29 CFR 1910.147 .

8. Piping Components

8.1 General

8.1.1 Recommended piping components are shown in the PIP Piping MaterialSpecifications Line Classe s. Other piping components and constructions thatare acceptable to the Code not mentioned in these Practices are permitted.

8.1.2 The minimum pipe size shall be NPS 3/4, except for Category D fluidservice, individual instrument leads, pump and compressor auxiliary piping,steam tracing, and for reduction at instruments or other equipment provided

with smaller than NPS 3/4 connections. Pipe sizes NPS 1-1/4, NPS 2-1/2, NPS 3-1/2, and NPS 5 should not be used, except for connections toequipment requiring these sizes and in jacketed pipe systems. In such cases,the transition to standard sizes shall be made as soon as practical.

8.1.3 Pipe sizes and schedules shown in the PIP Piping Material SpecificationsLine Classes are in accordance with ASME B36.10M and ASME B36.19M .


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8.2 Pipe

8.2.1 Nominal wall thickness for carbon and low-alloy steel pipe joined bywelding in new construction shall be, as a minimum, as follows:

a. Utility (Category D) fluid services

NPS 1/2 2 Not normally weldedNPS 3 6 StandardNPS 8 32 0.250 inch (6.4 mm)NPS 34 and larger Diameter/135

b. Normal and Category M fluid services

NPS 1/2 1-1/2 Extra strongNPS 2 6 StandardNPS 8 32 0.250 inch (6.4 mm)NPS 34 and larger Diameter/135

8.2.2 Nonferrous alloy and stainless steel (> 13% Cr) piping joined by welding innew construction shall be, as a minimum, as follows:

NPS 1/2 3/4 Schedule 40SNPS 1 and larger Schedule 10S

8.3 Joints and Fittings

8.3.1 Piping joints shall be of welded construction, unless otherwise specified.Flanges, unions, and threaded connections shall be used minimally, except inCategory D fluid services.

8.3.2 Butt-welded fittings shall be used for pipe greater than NPS 1-1/2, except as

required at equipment or control valve connections.8.3.3 Butt-welded or socket-welded fittings shall be used for pipe sizes not covered

in paragraph 8.3.2, except as follows:

a. Threaded fittings may be used downstream of a welded or flanged blockvalve to instruments, at equipment connections, and for terminal ventand drain connections.

b. Threaded fittings may be used for Category D fluid services.

8.3.4 Socket-welded and threaded constructions should be avoided in serviceswhere corrosion is accelerated in crevices.

8.3.5 In lube oil and seal oil lines, only butt-welded or flanged joints shall be used

between filters and equipment per API 614. 8.3.6 Butt-welded piping systems shall utilize long radius elbows. Short radius

elbows are permissible only where required by space limitations.

8.3.7 Flush bushings, close nipples, locknuts, street elbows, and street tees are not permitted.


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8.4 Branch Connections

8.4.1 Branch connections shall be at a 90-degree intersection to the run pipecenterline, unless otherwise specified. In no case shall a welded branchconnection be designed with an intersecting angle of less than 45-degrees,

unless approved by the owner.8.4.2 NPS 2 and Smaller

8.4.2.1 Straight tees shall be used when the branch size is equal to the headersize.

8.4.2.2 For header sizes NPS 2 and smaller, reducing tees (or straight teewith butt-welding reducer or swage nipple) shall be used when the

branch size is smaller than the header size.

8.4.2.3 For header sizes NPS 3 and larger, branch connections shall be madewith integrally reinforced branch connection fittings.

8.4.2.4 Integrally reinforced extended body valves per API 602 may be usedfor valved piping connections (e.g., pressure gauges, vents, anddrains).

8.4.3 NPS 3 and Larger

8.4.3.1 Branch connections shall be of all welded construction(e.g., unreinforced fabricated tees, reinforced fabricated tees,reducing tees, and forged integrally reinforced welded fittings).When the branch is the same size as the header, a straight tee shall beused.

8.4.3.2 Branch connections for piping at reciprocating equipment shall bewelding tees or forged integrally reinforced weld fittings.

8.4.4 Branch tables in the PIP Piping Material Specifications Line Classes providereinforcing pads designed for full area replacement.

8.4.5 Weep holes of 1/4-inch (6-mm) diameter shall be provided on reinforcing pads for branch connections, on wear pads, and on support reinforcing padsif they cover a weld that is not a pipe manufacturing seam weld. Weep holesshall also be provided to vent gases on piping that requires heat treatmentafter fabrication, or in special cases where hydrogen buildup could occur.Weep holes shall be packed with heavy grease.

8.4.6 Branch tables in the PIP Piping Material Specifications Line Classes reflectminimum requirements. The designer may select other equal or betterconfigurations to suit a particular project need.

8.5 Valves

8.5.1 General

8.5.1.1 Ball, butterfly, and plug valves shall have gear operators inaccordance with the PIP Piping Material Specifications Line Classes.


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8.5.1.2 Block valves and bypass valves at control valve manifolds,equipment, and pressure-reducing stations shall be of the higher

pressure rating.

8.5.1.3 For soft-seated valves, pressure-temperature ratings for the same

class valve may vary between manufacturers and may be lower thanthe ratings shown in PIP Piping Material Specifications Line Classes.

8.5.1.4 Screwed bonnet and screwed body valves shall not be used in anyhydrocarbon or hazardous material services unless the

bonnets/bodies are seal-welded.

8.5.1.5 Union bonnet valves shall not be used in any hydrocarbon orhazardous material services.

8.5.2 Gate Valves

Gear operators for wedge gate valves are recommended as follows:

Class Gate Valves Sizes (NPS)150 14 and larger

300 12 and larger

600 and 900 8 and larger

1500 and higher 6 and larger

8.5.3 Check Valves

8.5.3.1 Dual- and single-plate wafer check and swing check valves shall not be used in reciprocating pump and compressor suction and dischargeservices or similar pulsating services.

8.5.3.2 In parallel pump or compressor systems, check valves installed at thedischarge of pumps or compressors should be of a nonslam internal-spring-assisted type. Swing check valves should not be used in thisservice.

8.5.3.3 For parallel pump systems with individual pump discharge piping of NPS 20 and larger, a hydraulic analysis shall be conducted to verifythat the selected check valves have the correct dynamic response to

prevent slamming and limit pressure surge to an acceptable level.The analysis shall include consideration of the worst caseoperating mode scenario.


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8.5.4 Globe Valves

Gear operators for globe valves are recommended as follows:

Class Globe Valves Sizes (NPS)

150 14 and larger300 10 and larger

600 8 and larger

900 6 and larger

1500 4 and larger

2500 3 and larger

8.6 Flanges

8.6.1 Flanges in sizes NPS 24 and smaller shall be in accordance with ASME B16.5 for the listed materials. Steel flanges larger than NPS 24 shall be in accordance with ASME B16.47, Series B, unless otherwise specified.

8.6.2 The use of flanges in piping shall be minimized. Flanges are typically used:

a. At flanged equipment

b. At valves

c. At blanks

d. In removable sections of pipe

e. Where frequent dismantling of piping is required

f. Where piping lined with nonmetals or nonmetallic piping cannot be bonded or otherwise joined

g. To provide for erection requirementsh. To allow for modifications in areas where welding is not permitted

i. To provide clearance for dismantling of equipment (e.g., compressors,reactor heads, etc.)

j. For maintenance cleaning, decoking, or slurry service

8.6.3 Slip-on flanges may be used up to NPS 24 maximum in Classes 300 and below at design temperatures to 800 F (430 C).

8.6.4 Lap joint flanges may be used in Classes 300 and below at designtemperatures to 500F (260C).

8.6.5 Except for proprietary flanges, flange facing shall normally be raised-face forClasses 150 through 2500.

8.6.6 Flat-faced flanges with full-faced gaskets shall be used for connecting pipingto flat-faced flanged valves and equipment manufactured from nonductilematerials.

8.6.7 Flange facing finish for cast iron, ductile iron, and bronze shall be inaccordance with MSS SP-6 . Flange facing finish for steel, nickel alloy, andother alloys shall be in accordance with ASME B16.5.


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11.2 Plant Air

Plant air branch lines shall be taken from the top of the header. Block valves arerequired for branch connections less than NPS 2 and shall be located both at theheader and at the equipment.

11.3 Cooling Water

11.3.1 Block valves for every branch from cooling water supply and return headersshall be located either at the header or at the equipment being served. Blockvalves are not required on return lines operating at or below atmospheric

pressure unless needed for equipment or system isolation.

11.3.2 When exchangers are provided with process isolation valves for inspectionand cleaning during plant operation, block valves in the cooling water inletand outlet piping shall be provided. In freezing climates, an antifreeze bypassfrom the inlet to the outlet or other means to prevent freezing shall befurnished.

11.3.3 All aboveground cooling water supply and return branch lines shall beconnected to the top of the headers.

11.4 Utility Water

Utility water branch lines shall be taken from the top of the header. Block valves arerequired for branch connections less than NPS 2 and shall be located both at theheader and at the equipment.

11.5 Potable Water

11.5.1 Potable water shall not be connected to any other system unless isolated inaccordance with state and local requirements.

11.5.2 Connections to the potable water system shall be in accordance withapplicable ordinances and approved by the owner.

11.6 Steam and Steam Condensate Removal

11.6.1 Steam headers shall run level or shall pitch downward in the direction ofsteam flow. A vertical rise required in the direction of steam flow shall be viaa vertical leg equipped with a drip leg at the low point.

11.6.2 Steam branch lines shall be connected to the top of the headers. Branch linesshall run level or pitch downward in the direction of the steam flow. Avertical rise required in the direction of steam flow, downstream of theconnection to the steam header, shall be via a vertical leg equipped with adrip leg at the low point.

11.6.3 Block valves shall be provided in the branch lines from the steam headerslocated at and above the elevation of the steam header and installed in such amanner that no pocket is formed where condensate may collect.

11.6.4 Steam tracing shall be in accordance with PIP PNSC0035 (underdevelopment).


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11.6.5 Steam traps discharging into the atmosphere shall be provided with upstream block valves. Steam traps discharging to a condensate collection system shall be provided with both upstream and downstream block valves.

11.6.6 Condensate from vacuum steam systems shall be re-evaporated into the

system by means of a condensate flash pot or removed by eductors, pumpingtraps, or other suitable means.

11.6.8 All steam traps shall be provided with an internal strainer or a strainerlocated upstream of the trap. The strainer shall be equipped with a blowdownvalve piped to a safe location.

11.6.9 A steam separator or other means of condensate removal (e.g., pumping trap)shall be provided in the steam piping to each group of steam turbinesoperating on saturated steam and also to each group of steam-drivenreciprocating compressors and other water-sensitive equipment.

11.6.10 A minimum of one steam trap shall be provided for each steam separator,header drip leg, branch drip leg, and low point where condensate may collect.Each steam trap shall be sized and specified to operate at all anticipated

pressures and condensate loads for the installed location. Steam traps shall besized and specified to discharge noncondensable gases at the maximum ratesrequired to purge the steam system of these gases. Staged large and smallsteam traps may be required to handle large flows of condensate from start-up and small flows of condensate from normal operations.

11.6.11 Steam-trap discharge and other condensate lines shall be consolidated intoheaders and returned to the condensate collection system. Discharge to thewaste system may be made only if a collection system is not economicallyfeasible or if condensate is contaminated.

11.6.12 Drip legs equipped with steam traps shall be installed at the bottom of steamheaders as follows:

a. At dead ends of steam headers and branch lines

b. At low points

c. Upstream of risers and vertical legs

d. Upstream of expansion joints and raised expansion loops

e. Upstream of block, reducing, and control valves

f. At intervals of approximately 150 feet (45 m) in straight, horizontalsteam lines (i.e., without natural drainage points), but not greater than300 feet (90 m)

11.6.13 Provisions shall be made to protect steam and condensate lines from freezingwhere freezing conditions are encountered. Freeze protection shall include

provisions for operating locations and shutdown conditions.

11.7 Utility Stations

11.7.1 The following equipment shall have utility stations:


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a. Pump and compressor areas shall have permanent utility stations asfollows:

(1) Stations shall have steam, water, air, and nitrogen outlets as requiredfor anticipated needs.

(2) Station spacing shall be such that equipment can be covered with50-foot (15-m) hose lengths.

b. Columns and vessels shall have steam, water, air, and nitrogen, asrequired for anticipated needs.

c. Exchangers and furnaces shall be provided with steam, water, air, andnitrogen connections as required for anticipated needs. The locations ofthe connections shall be as specified by the owner.

11.7.2 Each utility take-off connection for steam, water, air, and nitrogen shall belocated at the top of the horizontal main header or auxiliary header. Rootvalves shall be provided for each utility take-off connection from a main

header or auxiliary header that cannot be taken out of service withoutshutting down a complete processing unit or operating facility.

11.7.3 Each utility line shall be provided with an isolation valve just upstream of thespecified hose connector at the termination. Pressure bleed-off valves shall

be provided in accordance with the owners requirements. Each line shallhave a service nameplate indicating the service. The utility pipe and the endsof hoses provided with the station shall be color-coded in accordance withthe location standard.

11.7.4 Color-coding and type of connectors shall be in accordance with the locationstandard.

11.7.5 Hose connections, where applicable, shall be positioned approximately 4 feet(1.2 m) above finished plant grade or above platform of multilevelequipment. The piping shall be securely bolted to a supporting structure.

11.7.6 When an overhead system is used in a freezing climate for water or steam,either an additional block valve shall be furnished at the header or othermeasures shall be taken to ensure that the piping is protected againstfreezing.

11.7.7 Hose connections to nitrogen systems shall have special fittings to provide positive segregation from the air system.

11.7.8 The nitrogen system shall have a check valve at each connection and at eachutility station to prevent the introduction of air or hydrocarbons into the

nitrogen system.11.7.9 Other requirements for utility stations shall be specified in accordance with

the location standard.

11.8 Burner Fuel Piping

11.8.1 Burner fuel piping shall conform to the following requirements:

a. Piping for fuel oil with viscosity exceeding 20 centistokes shall bearranged for continuous circulation of the oil through the headers.


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b. Fuel gas supply piping shall be arranged to produce equal distributionof flow and to allow condensate drainage, unless dry gas is assured.

11.8.2 Where a safety shutdown valve is required in fuel piping at furnaces or firedheaters, the valve shall have remote and local shutoff capability and shall be

located in close proximity (i.e., within 50 feet [15 meters]) to the equipment.An emergency shutoff valve shall always be provided at a safe distance(i.e., minimum of 50 feet [15 meters]) from the equipment.

11.9 Heat Transfer Fluid Piping

11.9.1 The use of flanged and threaded connections should be minimized. Weldedconstruction should be used wherever possible.

11.9.2 Any connection that is expected to be disassembled shall be provided with anupstream double block-and-bleed valve arrangement to protect personnel.

11.9.3 Some heat transfer fluids will freeze at ambient temperatures. Whenappropriate, heat tracing of the system should be provided to prevent freezingof lines when the system is shutdown.

11.9.4 If the piping system is cleaned or flushed using a water solution, the entiresystem should be thoroughly dried.

11.9.5 Thermal fluids have a high coefficient of thermal expansion. Therefore, provisions shall be made to safely absorb the increased volume at operatingtemperatures (e.g., an expansion tank).

12. Fabrication, Assembly, and Erection

Fabrication, assembly, and erection of piping systems shall be in accordance with PIP PNE00012, PIP PNSC0001, PIP PNSC0011, and PIP PNSC0021.

PNE00001

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