ASTM F722-18(2022)

Standard Specification for Welded Joints for Shipboard Piping Systems

ABSTRACT
This specification covers typical details of welded joints commonly used in shipboard piping systems. These joints and other joints may be used provided the welding procedures used have been qualified in accordance with the applicable regulatory rules and regulations. The maximum butt weld reinforcement of differnet nominal wall thicknesses of pipe or tube shall be discussed.
SCOPE
1.1 This specification covers typical details of welded joints commonly used in shipboard piping systems. These joints and other joints may be used provided the welding procedures used have been qualified in accordance with the applicable regulatory rules and regulations.  
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Sep-2022
• ICS: 25.160.40 - Welded joints and welds
• Technical Committee: F25 - Ships and Marine Technology
• Drafting Committee: F25.11 - Machinery and Piping Systems

Overview

ASTM F722-18(2022), "Standard Specification for Welded Joints for Shipboard Piping Systems," provides comprehensive specifications and typical details for welded joints used in shipboard piping. This international standard aims to promote quality, consistency, and safety by describing the details of butt-welded and fillet-welded joints in ship piping, as well as requirements for fabrication, service, and limitations. The standard applies to a wide range of piping systems and ensures that welding procedures are qualified under the applicable regulatory rules and standards, such as those set by the United States Coast Guard (USCG) and referenced ASME codes.

Key Topics

• Welded Joint Details:

  • Coverage of butt-welded joints for pipes, valves, fittings, and flanges.
  • Details for fillet-welded joints and fabricated joints, including outlet and boss connections.
  • Application, service, and limitations for each joint type are clearly outlined.

• Welding Procedures and Compliance:

  • Welded joints must meet qualified welding procedures adhering to regulatory and safety standards.
  • Maximum reinforcement for butt welds, including specific allowances based on pipe wall thickness and operating temperature.

• Piping Classifications and Service Conditions:

  • Specified for both Class I and II piping systems, covering various pressures, temperatures, and services (e.g., gravity drains, vents, overflows).

• Dimensional Controls and Inspection:

  • Requirements for internal/external alignment, minimum weld sizes, and acceptable welding practices for inspection and verification.
  • Clearly defined sizes, dimensions, and reinforcement limits for joint integrity.

Applications

This ASTM standard is essential for:

• Shipboard Piping Installations: Used extensively during ship construction or maintenance for all types of marine vessels, ensuring reliable welded connections in critical systems such as fuel delivery, water supply, steam, and hydraulic systems.
• Maritime Engineering and Fabrication: Shipyards, marine contractors, and welding professionals employ this standard to guide the selection and execution of welding techniques for piping assemblies.
• Regulatory Compliance: Ensures that shipboard piping systems meet USCG, ASME (like B31.1 Power Piping), and international requirements for operational and safety certification.
• Quality Assurance and Inspection: Supports shipowners, operators, and inspectors in verifying that welded joints are constructed to recognized, safe, and consistent standards.

Practical benefits include:

• Enhanced safety and reliability of shipboard fluids and gas transport.
• Standardized welding practices reduce risk of failure and extend system life.
• Simplified inspection and regulatory approval due to widespread industry acceptance.

Related Standards

• ASME B31.1 Power Piping – Describes design and fabrication of power piping systems referenced for miter joint design and welding procedures.
• 46 CFR (Code of Federal Regulations), Shipping – U.S. regulations governing marine piping, including key subparts referenced in ASTM F722 for piping classifications and weld reinforcement limits.
• Other ASTM Shipbuilding Standards – ASTM F721 (installation of piping systems), ASTM F1006 (performance of piping systems), and related marine and offshore standards.

Summary

ASTM F722-18(2022) is a valuable reference for shipbuilders, marine engineers, and regulators concerned with the quality, durability, and compliance of shipboard welded piping joints. By following its guidelines and leveraging its comprehensive application scope, stakeholders can achieve safer, longer-lasting, and regulation-compliant piping systems for marine environments.

Keywords: ASTM F722, welded shipboard piping, welded joints, marine piping systems, ship piping standard, welding procedures, butt-welds, fillet welds, maritime welding specification, ship piping compliance.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation:F722 −18 (Reapproved 2022) An American National Standard
Standard Specification for
Welded Joints for Shipboard Piping Systems
ThisstandardisissuedunderthefixeddesignationF722;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.1 Butt-Welded Joints for Pipes, Valves, Fittings, and
Flanges:
1.1 This specification covers typical details of welded joints
Fig. 1 Butt Joint, Square
commonly used in shipboard piping systems. These joints and
Fig. 2 Butt Joint, V-Grooved
other joints may be used provided the welding procedures used
Fig. 3 Butt Joint, V-Grooved, Welded Both Sides
have been qualified in accordance with the applicable regula-
Fig. 4 Butt Joint, Double V-Grooved, Welded Both Sides
tory rules and regulations.
Fig. 5 Butt Joint, Compound Bevel V-Grooved, Welded
1.2 The values stated in inch-pound units are to be regarded
Both Sides
as standard. The values given in parentheses are mathematical
Fig. 6 Butt Joint, V-Grooved, Miter Type
conversions to SI units that are provided for information only
Fig. 7 Butt Joint, V-Grooved, Welded with Bevel End-
and are not considered standard.
Type Backing Ring
1.3 This international standard was developed in accor-
Fig. 8 Butt Joint, Compound Bevel V-Grooved, Welded
dance with internationally recognized principles on standard-
with Bevel End-Type Backing Ring
ization established in the Decision on Principles for the
Fig. 9 Butt Joint, V-Grooved Welded with Bevel End
Development of International Standards, Guides and Recom-
Lug-Type Backing Ring
mendations issued by the World Trade Organization Technical
Fig. 10 Butt Joint, V-Grooved, Welded with Square End-
Barriers to Trade (TBT) Committee.
Type Backing Ring
2. Referenced Documents
Fig. 11 Butt Joint, V-Grooved, Welded with Consumable
Insert Ring
2.1 ASME Standards:
Fig. 12 Butt Joint, Compound Bevel V-Grooved, Welded
B31.1 Power Piping
with Consumable Insert Ring
2.2 Federal Standards:
Code of Federal Regulations Title 46 Fig. 13 Butt Joint, U-Grooved, Welded with Consumable
Shipping, Parts 41 to 69 Insert Ring
Fig. 14 Butt Joint, V-Grooved, Welded with Consumable
3. Application, Service, Limitations, and List of Weld
Insert Ring
Joint Details
Fig. 15 Butt Joint, Socket Weld to Socket Weld Valve,
3.1 Details of welded joints, including application, service,
Fitting or Flange Welded on Pipe Nipple
and limitation notes, are provided in the appropriate figures, as
Fig. 16 Butt Joint, Transition Between Unequal Inside and
follows:
Outside Diameter Components
3.1.2 Fillet Welded Joints for Valves, Fittings, and Flanges:
This specification is under the jurisdiction of ASTM Committee F25 on Ships
Fig. 17 Fillet Welded Sleeve-Type Pipe Coupling
and Marine Technology and is the direct responsibility of Subcommittee F25.11 on
Fig. 18 Fillet Welded Socket Weld Fitting or Valve
Machinery and Piping Systems.
Current edition approved Oct. 1, 2022. Published October 2022. Originally
Fig. 19 Fillet Welded Socket Weld-Flange
approved in 1981. Last previous edition approved in 2018 as F722 – 18. DOI:
Fig. 20 Double Fillet Welded Slip-On Flange (Forged)
10.1520/F0722-18R22.
Fig. 21 Double Fillet Welded Slip-On Flange (Plate Type)
Available from American Society of Mechanical Engineers (ASME), ASME
International Headquarters, Two Park Ave., New York, NY 10016-5990, http://
Fig. 22 Fillet Welded Slip-On Flange (Plate Type), Single
www.asme.org.
Bevel
Available from U.S. Government Printing Office, Superintendent of
Documents, 732 N. Capitol St., NW, Washington, DC 20401-0001, http://
www.access.gpo.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F722−18 (2022)
3.1.3 Fabricated Joints: Fig. 32 Fillet Reinforced External Root Connection,
Fig. 23 Fillet Welded Internal Root Connection Single Bevel with Integrally Reinforced Outlet
Fig. 24 Fillet Welded External Root Connection Fig. 33 Fillet Reinforced External Root Connection
Fig. 25 Fillet Reinforced External Root Connection Single Welded Both Sides, Single Bevel with Integrally Reinforced
Bevel Outlet
Fig. 26 Fillet Reinforced External Root Connection,
Single Bevel, Welded Both Sides 4. Piping Classifications and Butt Weld Reinforcements
Fig. 27 Fillet Reinforced External Root Connection,
4.1 Piping classifications in accordance with Subpart 56.04
Single Bevel, Welded with Square End Backing Ring
of USCG Regulations apply to this specification.
Fig. 28 Fillet Reinforced Internal Root Connection, Single
4.2 Maximum thickness of butt weld reinforcements in
Bevel, Welded with Square End Backing Ring
accordance with 46 CFR Subpart 56.70, Table 56.70-15, of
3.1.4 Outlet and Boss Connections:
USCG Regulations are listed in Table 1.
Fig. 29 Fillet Reinforced Boss Connection Without Pilot,
Single Bevel
5. Keywords
Fig. 30 Fillet Reinforced Boss Connection with Pilot,
Single Bevel 5.1 backing ring pipe welds; boss connections; flange
Fig. 31 Fillet Reinforced Boss Connection (Couplet) with welds; miter joint weld; pipe welds; root connections; sleeve
Integral Backing Ring pipe welds; socket welds; welded joints
F722−18 (2022)
⁄16 in. = 2 mm
⁄8 in. = 3 mm
⁄8 in. = 3 mm
⁄16 in. = 5 mm
⁄8 in. = 22 mm
Application—Class II piping.
Application—Class I and II piping above 2-in. NPS.
Systems or Service—For services such as gravity drains (including plumbing),
System or Service—All.
vents, and overflows.
Remarks—1. Internal weld shall be made first and ground, chipped, or cleaned
Remarks—1. Root of weld need not be ground.
by some other means to assure sound welds.
FIG. 1 Butt Joint, Square
2. The “L” dimension should be held to a minimum to facilitate welding and
inspection on the inside surface of the pipe.
FIG. 3 Butt, Joint, V-Grooved, Welded Both Sides
⁄16 in. = 2 mm
⁄16 in. = 2 mm
1 ⁄8 in. = 3 mm
⁄8 in. = 3 mm
⁄8 in. = 22 mm
⁄8 in. = 22 mm
Application—Class I and II piping above 2-in. NPS.
Application—Class II piping.
System or Service—All.
System or Service—All provided root of weld is visually inspected where
Remarks—1. Internal weld shall be made first and ground, chipped, or cleaned
possible to ensure complete weld penetration.
by some other means to assure sound welds.
Remarks—1. For services such as vents, overflows, and gravity drains (includ-
2. The “L” dimension should be held to a minimum to facilitate welding and
ing plumbing) the root of the weld need not be ground.
inspection on the inside surface of the pipe.
FIG. 2 Butt Joint, V-Grooved
FIG. 4 Butt Joint, Double V-Grooved, Welded Both Sides
F722−18 (2022)
1 1 3 7
in. ⁄16 ⁄8 ⁄16 ⁄8
mm 2 3 5 22
1 1 3 7
in. ⁄16 ⁄8 ⁄4 ⁄8
Application—Class I and II piping.
mm 2 3 19 22
System or Service—All, except as noted in remarks.
Remarks—1. Backing ring may be tack-welded in place to facilitate fabrication.
Application—Class I and II piping above 2-in. NPS.
2. When used in the following services, backing rings shall be removed.
Systems or Service—All.
(A) Lube oil service discharge piping from the lube oil pumps to the reduction
Remarks—1. Internal weld shall be made first and ground, chipped, or cleaned
gears, HP and LP turbines, and lube oil gravity tank.
by some other means to assure sound welds.
(B) Superheated steam outlet piping from the main boilers to the HP and LP
2. The “L” dimension should be held to a minimum to facilitate welding and
turbines and turbo generators and desuperheated steam from the main boilers to
inspection on the inside surface of the pipe.
turbine driven main feed pumps.
(C) Central hydraulic systems.
FIG. 5 Butt Joint, Compound Bevel V-Grooved, Welded Both
FIG. 7 Butt Joint, V-Grooved, Welded with Bevel End-Type
Sides
Backing Ring
1 1 1 3 3 7
⁄16 in. = 2 mm
in. ⁄16 ⁄8 ⁄4 ⁄8 ⁄4 ⁄8
⁄8 in. = 3 mm
mm 2 3 6 10 19 22
⁄8 in. = 22 mm
Application—Class I and II piping.
Application—Class II piping where use will not cause objectionable pressure
System or Service—All, except as noted in remarks.
drop or turbulence.
Remarks—1. Backing ring may be tack-welded in place to facilitate fabrication.
System or Service—All provided root of weld is visually inspected where
2. When used in the following services, backing rings shall be removed.
possible to ensure complete weld penetration.
(A) Lube oil service discharge piping from the lube oil pumps to the reduction
Remarks—1. For services such as vents, overflows, and gravity drains (includ-
gears, HP and LP turbines, and lube oil gravity tank.
ing plumbing), the root of the weld need not be ground.
(B) Superheated steam outlet piping from the main boilers to the HP and LP
2. Miter segments shall be designed in accordance with ASME B31.1, para-
turbines and turbo generators and desuperheated steam from the main boilers to
graph 104.3.3, and 46 CFR 56.07-10(f).
turbine driven main feed pumps.
FIG. 6 Butt Joint, V-Grooved, Miter Type (C) Central hydraulic systems.
FIG. 8 Butt Joint, Compound Bevel V-Grooved, Welded with
Bevel End-Type Backing Ring
F722−18 (2022)
1 1 1 3 7
in. ⁄64 ⁄32 ⁄16 ⁄4 ⁄8
⁄8 in. = 22 mm
mm 0.4 1 2 19 22
Application—Class I and II piping.
Application—Class I and II piping.
Systems or Service—All, except as noted in remarks.
System or Service—All.
Remarks—1. Backing ring may be tack-welded in place to facilitate fabrication. 1
Remarks—1. Internal misalignment of pipes shall not exceed ⁄16 in. (2 mm).
2. When used in the following services, backing rings shall be removed.
2. Consumable insert ring shall be centered before welding.
(A) Lube oil service discharge piping from the lube oil pumps to the reduction
FIG. 12 Butt Joint, Compound Bevel V-Grooved, Welded with
gears, HP and LP turbines, and lube oil gravity tank.
Consumable Insert Ring
(B) Superheated steam outlet piping from the main boilers to the HP and LP
turbines and turbo generators and desuperheated steam from the main boilers to
turbine driven main feed pumps.
(C) Central hydraulic systems.
FIG. 9 Butt Joint, V-Grooved Welded with Bevel End Lug-Type
Backing Ring
1 1 1 3
in. ⁄64 ⁄32 ⁄16 ⁄16
mm 0.4 1 2 5
Application—Class I and II Piping.
System or Service—All.
1 1 3 7
Remarks—1. Internal misalignment of pipes shall not exceed ⁄16 in. (2 mm).
in. ⁄16 ⁄8 ⁄16 ⁄8
2. Consumable insert ring shall be centered before welding.
mm 2 3 5 22
FIG. 13 Butt Joint, U-Grooved, Welded with Consumable Insert
Application—Class I and II piping.
Ring
Systems or Service—All.
Remarks—1. After welding, backing ring shall be machined flush with inside
diameter of pipe or fitting.
FIG. 10 Butt Joint, V-Grooved, Welded with Square End-Type
Backing Ring
0.020 in. = 0.51 mm
Application—Class I and II piping.
System or Service—All.
Remarks—1. Internal misalignment of pipes shall not exceed ⁄32 in. (1 mm).
1 1 1 7
in. ⁄64 ⁄32 ⁄16 ⁄8
2. Consumable insert ring shall be centered before welding.
mm 0.4 1 2 22
FIG. 14 Butt Joint, V-Grooved, Welded with Consumable Insert
Ring
Application—Class I and II piping.
System or Service—All.
Remarks—1. I
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