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Minimum Distance Between Welds as per International Codes and Standards

Welding is a fabrication process that permanently joins two or more pieces of metal together. It is one of the most common joining techniques used in the manufacturing industry and is used to create products of all shapes and sizes. Welding involves the use of heat and/or pressure to melt the two pieces of metal together and then fuse them. There are several different types of welding processes, including arc welding, MIG welding, TIG welding, and oxy-acetylene welding. Each process has its own advantages and disadvantages, so it is important to select the most appropriate process for the particular application.

Arc welding process is an arc welding process in which an electric arc is used to produce coalescence of metals. The process uses a consumable electrode that is continuously fed into the weld joint. The arc is generated between the electrode and the workpiece, which produces an intense heat that melts the metals and causes them to join together. The process can be used on a variety of metals and alloys and is used to weld components in a wide range of industries.

Minimum Distance Between Welds as per International Codes and Standards

The minimum distance between welds depends on the type of welding process being used. Generally, the minimum distance between welds is determined by the type of material being welded, joint design, and welding process parameters. For example, the minimum distance between fillet welds is typically 1/16 inch (1.6 mm). However, this can vary depending on the material, joint design and welding process.

Standard / Spec.

Minimum Distance Between Welds


Vessel Code-2017

Longitudinal welds 5t unless circumferential welds are tested by RT up to 4" on each side

If impact test as per UCS-66 required the min distance cannot be exempted by RT. No Limit for Circumferential

ASME IX. 2013

Longitudinal welds 5t unless circumferential welds are tested by RT

up to 4" on each side

In vessels with two or more courses, longitudinal joints of adjacent

courses staggered or separated 5t, t= thickness of thicker plate.

ASME B31.3 - 2016

5t or 30 degrees off for Longitudinal. No Limit for Circumferential

ASME B 31.4-2016

ASME B31.8 - 2016

1/2 ND between miter crotches

Consideration shall be given to the toughness characteristics and

quality of all seam welds in repair welds.

API 5L/ISO 3183-2012

Longitudinal: 50-200 mm

Circumferential. 1500mm

API 650-2014

5t between vertical welds

BS 2633-2006

4t, where t= nominal thickness of the pipe

BS 4515-2006

4t, where t= pipe thickness

BS 2971-2009

Agreed by parties

BS PD 5500 - 2014

Longitudinal welds, 4t or 100mm

AS 4458

Circumferential 4t or 30 mm

Non-pressure parts: the lower of 3t or 40 mm

The exception is made when the first weld is subject to PWHT

AS 4041-2006

4t or 40 mm

EN12952-5 -2001

But weld of tubes:

2D for t<250 .where D = Outside diameter of tube

500 for t>250; where t= Drum or Head thickness

Spacing between attachment weld and Main joint weld min 40mm.

Branch opening and Main weld:

2t for t<25

50 for t>25

If not practical, cross completely and ground flush and perform NDT


Longitudinal 30 degree staggered. Circumferential: 500mm


Circumferential: lD or 500mm

Between branch/attachment and girth 4t or 100mm

ARAMCO 32-SAMSS-004-2008

Welds of shell-head and head-skirt to be separated min 1 inch

ARAMCO SAES-W-012-2008

Longitudinal welds of adjacent pipe joints shall be 100 mm.

Butt welds 20 mm or 3t whichever is greater.

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