Proximity of butt welds / amendments (ASME rules?)

[lgracio]

I'm working on Manufacturing of Boilers. Anyone know how should I proceed if an additional weld or emend must be done regarding insufficient raw material length? My concern is about the secure distances between weldments/emends, how should I proceed if a boiler was designed according ASME+PED? For my client this is an anomalous situation on manufacturing side, and such weldment was not considered or specified by designer?

On boiler code EN12952-5, on section 8.11.4, regarding proximity of butt welds, is referred that for tube diameters up to and including 250mm, butt welds shall not be positioned closer than twice the outside diameter of the tube. When the outside of the tube is greater than 250mm, butt welds shall not be positioned closer than 500mm.

What about ASME code? Anyone can help me?

 

[CodeRef]

See the following threads

thread292-147793

thread292-207026

thread292-194119

thread292-182647

thread378-106738

Good Luck!

 

[lgracio]

Somebody know how should I proceed on ASME code for allowable spacing between branches and main joint welds?

EN 12952-5, section 8.1.7 gives a table with allowed spacing related pipe thickness:
- Thk less and equal 25mm spacing shall be greater than 2 times the Thk;
- Thk greater than 25mm spacing shall be greater than 50mm.

Luís Grácio
Mechanical Engineer (Energy Solutions)
Portugal-Setúbal

 

[pipewelder1999]

A b31.1 Interpretation says

Interpretation: B31.1-22-7
Subject: B31.1, 127.4, Welding
Requirements
Date Issued: December 10, 1992
File: B31-92-027

Question: Does the B31.1 Code require that a
minimum distance be maintained between adjacent
piping welds.

Reply: No. However, refer to paragraph
104.3.1(G.7) for rules regarding the reinforcement
of multiple openings.

B31.3 Says

Interpretation: B31.3-7-02
Subject: B31.3-1987, Paras. 304.3.3 and
328; Spacing of Welds
Date Issued: May 24, 1988
File: B31-87-039

Question: In accordance with B31.3, are there
requirements or guidelines on the minimum distance
between welds in a pipe?

Reply: No, except as provided in paragraph
304.3.3(e).


Para 304.3.3(e)refers to overlapping of reinforcement zones.

Is there an engineering reason based on past history or failures to restrict the spacing between welds?

I know when I was in the Navy, it was restricted on socket welds to 5T BUT it could be less provided the groove formed was filled to flush with 1T.

Have a good day

gerald



Gerald Austin
Iuka, Mississippi

http://www.weldinginspectionsvcs.com

 

[gr2vessels]

Hi igracio,
The ASME Code is not specifying a minimum distance, because the risk of mis-interpretations and incorrect aplications. Other Codes like EN or even Australian one, do specify minimum distance of 3 times the shell thickness between the weld toes or 40 mm, which ever is smaller.
The typical reason is the potential damage to the material structure the weld could do;- the close proximity of two HAZ could compromise the material specific properties and could be unexpected source of equipment failure. However, this is not a fully valid statement, since welds are rutinely cris-crossing on a pressure vessel, without any damaging consequences, under controlled situations. There are post weld stress relieving heat treatments which are required to minimise the impact of weld induced stresses, including those in close proximity or crossing each other.
Cheers,
gr2vessels

 

[pipewelder1999]

gr2vessels,

Are there any refernce materials that you know of that describe the possible problems from adjacent welds? I am a welding inspector and not an engineer. I would be interested in any refernce materials.

Gerald Austin
Iuka, Mississippi

http://www.weldinginspectionsvcs.com