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Piping Drawings Checking Procedure

Posted by Antony Thomas at Tuesday, October 26, 2010

CHECKING PIPING DRAWINGS PROCEDURE


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DISCLAIMER

This Procedure is intent to prepare for the Piping Checkers perfection. Piping Info accepts no
liability or responsibility whatsoever for it in respect of any use of or reliance upon this procedure
by anyone or any entity.

1.0 PURPOSE

The purpose of this design procedure is to ensure accuracy and completeness of piping drawings
issued by the Mechanical Design Department; and identify responsibility, criteria, and specific items
to be checked by the Mechanical Design Checker.

2.0 MECHANICAL DESIGN CHECKER RESPONSIBILITY

2.1 Responsible that the piping drawings are complete, accurate, interference free,
constructible, maintainable, in compliance with System Design and Checking Guides,
standards, standard deliverable drawings, project design criteria, vendor data, Process
and Instrument Diagram (P&ID), project contract, and engineering requirements.
2.2 Responsible to verify the location and limits of drawing HOLDs to areas that are
incomplete or can not be verified and approved by the checker prior to issue due to
insufficient engineering, vendor, client or other discipline information.
2.3 Responsible to verify that all reference data and documents used to perform the check
are the most current available. This includes vendor drawings, P&ID’s, design criteria,
thermal analysis, other discipline drawings and models. Use the Designed Piping
System Folder that contains design information gathered by the Designer and Lead
Designer for each system.
2.4 Use a hard copy “check print” of the drawings for marking comments in red for
correction that include additions, changes, or deletions. Graphics, dimensions, and
notes that are verified to be correct shall be highlighted in yellow. Comments, notes,
references, etc that are not for correction shall be made in black graphite pencil.
2.5 Upon completion of the initial drawing check, the Checker shall return the check prints
to the originator or Lead Mechanical Designer for correction along with the Designed
Piping System Folder. After correction, the Checker is responsible to “back check” the
drawing to assure all corrections and engineering comments were incorporated
accurately.
2.6 Responsible to check the complete content of the drawing and piping system design
including but not limited to all items contained in this procedure. The checker shall
contact the Mechanical Lead Designer or Engineer for additional project specific
requirements.
2.7 Responsible to maintain check prints, records, and information until the piping system is
fabricated, installed, and operating.
CHECKING PIPING DRAWINGS PROCEDURE
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3.0 DRAWING INFORMATION CHECK

3.1 Drawing Number. Check that the drawing number is in accordance with the project
numbering system, client numbering system.
3.2 Drawing Revision Number/Letter and Description. Check that the drawing revision
number/letter is correct in the title block and revision description block according to
project revision numbering system. Check that the revision description in the revision
block describes the purpose for the drawing issue or changes.
3.3 Drawing Title Block Information. Check that the text in the drawing title block is correct
in accordance with the project standards Deliverable Drawings.
- Project Description
- Drawing Type Description (Piping Isometric, Underground Piping Isometric, Small
Bore Piping Isometric, Analyzed Small Bore Piping, etc)
- Piping System Description
- Scale
3.4 Drawing Signatures. Check that drawing signatures are correct in the title block.
3.5 Back Circles. For revised drawings only, check that back circles are place around
revised areas to identify changes since the previous drawing issue. Check that back
circles from previous revisions have been removed.
3.6 Drawing Notes. Check that general and specific notes are in accordance with the
example on WorleyParsons’ Standard Deliverable Drawings and are applicable to the
drawing content and project specific requirements.
- Check drawing number references listed within the general notes.
- Check Technical Specification number listed within the general notes.
- Check Insulation Specification number listed within the general notes.
3.7 Drawing Attributes. Check that the line graphic and text attributes meet the
requirements of the Project Cadd Specification.
3.8 Spelling and Abbreviations. Check the spelling of all text and abbreviations within the
drawing. Periods after abbreviations are not required.
3.9 North Arrow. Check that a north arrow is on the drawing, including at detail plan views.
3.10 Project Specific Requirements. Check with the Lead Designer and Project Design
Criteria for any project specific drawing or pipe system requirements.
4.0 PIPING SYSTEM INFORMATION CHECK
4.1 System to P&ID Check. Check that the pipe system matches the approved system P&ID
including comments found on the project’s Master Set of P&ID’s. The checker is
responsible that the piping drawing and the P&ID are in agreement for the following:
CHECKING PIPING DRAWINGS PROCEDURE
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- Pipe Line Number
- Pipe Sizes
- Pipe Line Specifications and locations of Line Spec changes within the pipeline.
- Pipe Insulation Class
- Branch and Component sequence
- Equipment Tag Numbers and Descriptions
- Component Tag Numbers
- Flow direction
- Heat Tracing limits, type, and thickness
4.2 Equipment Location, Description, Tag Number. Check the coordinate (n/s, e/w, and
elevation) locations of all equipment to which the pipe system is connected in the model.
The location shall match the general arrangement, equipment setting plan, and
civil/structural drawings. Check that the equipment description and tag number match the
P&ID and Mechanical Equipment List.
4.3 Equipment Nozzle Location, Tag Number and Data. Check the equipment model nozzle
location, size, connection end preparation, flange rating, pipe schedule are in accordance
with the latest equipment vendor drawing.
- Check that nozzle information on piping drawing is correct
- Butt Weld nozzles shall include the nozzle pipe schedule or wall thickness
4.4 Piping Connection to Equipment Nozzle. Check the pipe connecting to the equipment
nozzle matches the nozzle attributes and is compatible.
- Flat Faced or Raised Faced Flanges
- Butt Weld Nozzles requires matching material and pipe wall thickness. Identify
dissimilar metal welds and wall thickness between nozzles and pipe.
- Non-USA vendor may provide nozzles that do not comply with ASME B16.25 weld
bevel standards. Identify locations of any pipe joint that requires a bevel different than
the ASME standard.
4.5 Flow Direction Arrow. Check that each pipe line contains one flow direction arrow. Each
sheet of a piping isometric shall contain a minimum of one flow direction arrow.
4.6 Completeness. Check that all dimensions, notes, information, and details that are
required for the construction and installation of the piping are included.
- Compliance with System Design Guides. Check that the piping system is designed in
accordance with the Mechanical Design Department specific system design guides.
4.7 Project System Design Criteria Documents. Check that the piping system is designed in
compliance with project/client design criteria documents.
4.8 Valve and In-Line Components. Check all valves and in-line pipe components (flow
elements, expansions joints, orifice plates, restricting orifices, etc) end to end dimensions
and connection attributes from approved vendor drawings. Check that the connection
size, type and schedule match the attributes of the pipe. Check all valve actuators for
correct size, orientation and that they are accessible for operation and maintenance.
CHECKING PIPING DRAWINGS PROCEDURE
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- Standard end to end dimensions per ASME/ANSI B16.10 for valves 600 lb class and
below may be approved without approved vendor drawings for gates, globe, and
check valves. All other valves shall be on hold until approved vendor drawings are
available.
- Butterfly, control, ball, plug, and relief valve end to end dimensions do not conform to
end to end standards and shall be on hold until approved vendor drawings are
available.
- Identify dissimilar metal welds and wall thickness between component and pipe.
-
- Check that chain wheel operators are provided on non accessible valves.
4.9 Valve, Flow Element, and In-Line Component Installation Requirements.
Check vendor drawings and installation instructions for installation requirements of
valves, flow elements and in-line components within the pipeline.
- Straight pipe upstream and downstream requirements
- Valve stem orientation (especially butterfly valves)
- Clearances for valve maintenance and disassembly.
- Lugged butterfly valves shall be noted on drawings for proper bolting procurement.
- No gaskets required at low pressure butterfly valves and expansions joints.
- Flat face flanges required at flanged expansion joints
- Flat face flanges are required at cast iron equipment flanges
- Flow element upstream and downstream straight pipe requirements according to the
Control System Engineer requirements.
4.10 Vents and Drains. Check quantity and location of vents and drains. Check that all vent
and drain connections reference the correct standard detail number.
4.12 Minimum pipe spool lengths. Check that there are adequate pipe spool lengths
between pipe line components. Use the following as a guide. Large Bore Butt Weld:
Minimum spool length equivalent to the length of a butt weld reducer. Small Bore
Socket Weld: Minimum exposed pipe length between socket weld components ends
shall be 2”.
4.13 Separation Distances for Branches. Check that there is adequate separation distance
between pipe branches and adequate separation distances between branches and
pipe line ends or components.
4.14 Instrument Connection Orientation and Access. Check that instrument connections
that require access are accessible and that the orientation on the pipe is correct.
Check for proper connection type and size. Check that all Instrument connections
reference the correct standard detail number, and there are sufficient clearances for
element removal from pipe.
- Temperature connections shall be located downstream of pressure connections.
- Temperature thermowells cannot be installed in pipes smaller than 3”.
4.15 Insulation and Insulation Support Lugs. Check insulation requirements to Project
insulation class codes and thickness. Add insulation support lugs on vertical runs of
alloy pipe.
CHECKING PIPING DRAWINGS PROCEDURE
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4.16 Heat Tracing. Check that piping is Heat Traced as identified on the system P&ID and
in accordance with the Project Heat Tracing Criteria.
4.17 Pipe Penetrations symbols. Check that all concrete floor, platform grating, wall, and
grade penetrations are indicated and labeled on piping isometrics. Callout core drilled
openings in existing walls when required.
4.18 Waterstops. Check that water stops are provided on underground piping at floor and
wall penetrations.
4.19 Slope. Check that pipe systems that require slope have the proper minimum slope
and the correct slope direction. For hot piping verify pipe does not reverse slope in hot
position.
4.20 Pipe Supports and Welded Attachments. Check that pipe supports are shown when
required and locations, quantity, and tag numbers have been review and approved by
the Piping Engineering department. Check that shop welded pipe support attachment
details are provided on alloy piping for shop welding before shop stress relieving.
4.21 Material List on Isometrics. Check that all pipe and pipe component material
descriptions in the isometric drawing material list matches the engineering pipe line
specification.
4.22 Insulating Flange Kits. Check that insulating flange kits are identified on aboveground
piping systems connecting to underground pipe systems where required by the
pipeline specification.
4.23 Dissimilar Metal Welds. Check that dissimilar metal welds that may occur at valves,
equipment nozzles, and material spec changes are identified and transition pieces are
provided if required.
4.24 Dissimilar pipe and/or component wall thickness. Check that dissimilar pipe and
component wall thicknesses that may occur at valves, equipment nozzles, and at
material spec changes are identified and transition pieces or taper bores are provided
if required. ASME Power Piping Code B31.1 Section 127.3C allows a 1/16” (.0625”)
internal pipe wall misalignment (each side) for welding without taper boring the
connecting pipe. Example of piping drawing identification of dissimilar wall thickness
taper bore: TAPER BORE SCH 160 PIPE TO MATCH SCH 80 VALVE
5.0 PIPING SYSTEM ROUTING AND LAYOUT CHECK
5.1 Interference Check. Check that the system is interference free by a visual review of the
model and that a recent electronic interference report from the model had been reviewed
and cleared. If a non 3D project, review all discipline reference drawings. If the pipe
routing is within an existing plant area, verify a field interference check was performed.
For hot piping verify pipe clearances in hot positions.
5.2 Thermal Analysis. For hot piping verify WorleyParsons Piping Engineering Department
has approved the thermal flexibility of the pipe. Checker is responsible to obtain pipe
CHECKING PIPING DRAWINGS PROCEDURE
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thermal movements and verify clearances in hot position and that pipe does not reverse
slope causing low point pockets. Thermal movement’s direction and distance shall be
noted on check prints in blue for future reference.
5.3 Hazardous Areas. Check that no electronic instrument, valve actuator, or other electronic
component within the pipe or attached to the pipe falls within a Hazardous Area of the
plant.
5.4 Plant Personnel Access, Construction Access, Maintenance Areas, and Safety. Check
that the pipe system layout does not obstruct plant personnel access, construction
access, and maintenance areas of the plant. Check that the pipe system lowest
appendage (including pipe support clamps) is above 6’-8” headroom and does not affect
plant safety.
5.5 Pump and Equipment Requirements. Check that the pipe system layout meets the
requirements of the connecting equipment vendor requirements or common practice.
The checker shall read all vendor criteria. Examples:
- Pump suction straight diameters, eccentric reducers
- Steam Turbine vendor requirements
- Check pipe system against Equipment Vendor P&ID if applicable
- Installation and Maintenance Manuals
5.6 System Discharge Points. Check that safety valve discharges, gas vents, etc are
discharged in a safe location that will not be harmful to personnel, structures, or
equipment. Confirm safety valve discharges do no impact noise abatement requirements.
Confirm gas (fuel gas, hydrogen) discharge points are indicated on hazardous area
location drawings.
5.7 Underground Pipe Burial Depth. Check that underground pipe has adequate cover to
protect from crushing from vehicle, railroad, and crane loads and is below frost depth.
5.8 Pipe Lanes. Check that pipe system layout is within established pipe north/south,
east/west pipe lanes and elevations established within the plant. Underground piping shall
have common bottom of pipe elevations for trenching.
5.9 Structural Gusset Plates. Check that the pipe system does not interfere with areas to be
occupied by structural gusset plates. Not all gusset plates are in the model and those
that are modeled may not represent the actual structural fabricators detail and
requirements. Checkers must do a visual model interference check at gusset plate areas
and interface with structural design to assure sufficient clearances.
5.10 Circulating Water Branch Component Reinforcement Plate clearance. Check for
potential interferences in the area of large pipe component reinforcement plates,
especially at crotch areas of laterals.
5.11 Underground Potable Water and Waste Water Separation. Check local and state
codes for separation requirements between underground potable water and waste
water systems to prevent pollution of potable water.
CHECKING PIPING DRAWINGS PROCEDURE
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5.12 HDPE Pipe Fitting Separation and Butterfly Valves. Check that there are pipe spools
between all HDPE pipe fittings to accommodate differences in physical dimensions
between HDPE fitting manufactures. Check that Butterfly Valves discs are not
obstructed from opening when connected to heavy wall HDPE pipe. Pipe spacers
may be required between the flange and valve body.
5.13 Clearance from vertical structural columns and walls. Check that pipe routing
maintains approximately 9 inches of clearance from vertical structural columns and walls
(including hot position) to allow space for field routed utilities.
5.14 ‘Olet Branch Dimensions. ‘ Olet type pipe branch fittings (weldolet, sweepolet, etc)
dimensions (run pipe centerline to the fitting outlet) are approximate because the
dimension varies by manufacture. Check that fitting to fitting design on the outlet of
the ‘olet branch fittings is not used. A pipe spool is required for adjustment by the pipe
fabricator to suit actual fitting dimensions while maintaining the overall geometry of
the pipe system.
5.15 Miscellaneous Items for Checking List. Includes commonly found piping isometric
Isogen software errors requiring manual annotation.
a) Orifice Flange pressure tap orientations incorrectly shown by Isogen.
b) Dimensions or dimension strings starting at pipe caps. Isogen dimension is
from cap work point (center of cap where blue line stops) but dimensions
on drawing appears to be from end of cap.
c) Eccentric Reducer offset dimensions incorrectly shown by Isogen do not
match actual fitting offsets as manufactured and should be deleted.
6.0 HOLDS CHECK
6.1 Holds. Check the location and limits of drawing HOLDs to areas of the drawing that are
incomplete or can not be verified and approved by the checker prior to issue due to
insufficient engineering, vendor, client or other discipline information. See Section 2.2.
6.2 Hold List. Check that all drawing holds are included in the Holds List for the project.
7.0 PIPING DRAWING CHECK LIST
7.1 Check List. A summary of the items identified in this procedure is provided in
ATTACHMENT 1 “Piping Drawing Check List”.
This list may be printed and used as a checking tool or record at the discretion of the
Mechanical Design Checker.
CHECKING PIPING DRAWINGS PROCEDURE
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ATTACHMENT 1

PIPING DRAWING CHECK LIST
DRAWING INFORMATION CHECK
3.1 Drawing Number
3.2 Drawing Revision Number/Letter and Description
3.3 Drawing Title Block Information
3.4 Drawing Signatures
3.5 Back Circles
3.6 Drawing Notes
3.7 Drawing Attributes
3.8 Spelling and Abbreviations
3.9 North Arrow
3.10 Project Specific Requirements
PIPING SYSTEM INFORMATION CHECK
4.1 System to P&ID Check
4.2 Equipment Location, Description, Tag Number
4.3 Equipment Nozzle Location, Tag Number, and Data
4.4 Piping Connection to Equipment Nozzle
4.5 Flow Direction Arrow
4.6 Completeness (All required dimensions, notes, information, details required for
construction)
4.7 Compliance with System Design Guides
4.8 Project Design Criteria Documents
4.9 Valve and In-Line Components
4.10 Valve, Flow Element, and In-Line Components Installation Requirements
4.11 Vents and Drains
4.12 Minimum Pipe Spool Lengths
4.13 Separation Distances for Branches
4.14 Instrument Connection Orientation and Access
4.15 Insulation and Insulation Support Lugs
Heat Tracing
Pipe Penetration Symbols and/or callout of core drilled openings
Waterstops
Slope
Pipe Supports and Welded Attachments
Material List on Isometrics
Insulating Flange Kits
Dissimilar Metal Welds
Dissimilar pipe and/or component wall thickness
CHECKING PIPING DRAWINGS PROCEDURE
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ATTACHMENT 1 (CONTINUED)

PIPING DRAWING CHECKLIST
PIPING SYSTEM ROUTING AND LAYOUT CHECK
5.1 Interference Check
5.2 Thermal Analysis
5.3 Hazardous Areas
5.4 Plant Personnel Access, Construction Access, Maintenance Areas, and Safety
5.5 Pump and Equipment Requirements
5.6 System Discharge Points
5.7 Underground Pipe Burial Depth
5.8 Pipe Lanes
5.9 Structural Gusset Plates
5.10 Circulating Water Branch Component Reinforcement Plate clearance
5.11 Underground Potable Water and Waste Water Separation
5.12 HDPE Pipe Fitting Separation and Butterfly Valves
5.13 Clearance from vertical structural columns and walls
5.14 ‘Olet Branch Dimensions
5.15 Miscellaneous Items for Checking List
HOLDS CHECK
6.1 Holds
6.2 Holds list

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