structural attachment by welding after the hydro test on pipeline

[QC7]

Hello gentlemen,


Are we permitted to attach some clips or structural attachment by welding after the hydro-static or leak test on the pipeline in accordance with code B 31.4

I cannot find anything in B 31.4 that definitively states that a re-hydrotest must be performed after the addition of the attachment by welding.

Please provide your comments in accord with B31.4


Regards,

QC7

 

[LittleInch]

What section 437.1 says is

437.1.4 Testing After New Construction
(a) Systems or Parts of Systems
(1) All liquid and slurry transportation piping systems within the scope of this Code, regardless of stress,
shall be tested after construction.

In my opinion this counts as "New construction", therefore 437.1.4.a) 1) applies

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[1503-44]

Butt, butt ...

404.9 Supports, Braces, Anchors, and Attachments
404.9.1 General. The applicable sections of MSS SP-58 for materials and design of pipe hangers and supports and of MSS SP-69 for their selection and application may be used.
If pipe is designed to operate above 20% SMYS, all attachments welded to the pipe shall be made to a separate cylindrical member that completely encircles the pipe and this encircling member shall be welded to the pipe, by continuous circumferential welds.

 

[QC7]

Hi LittleInch,

I agreed clause 437.1.4 (a) & 2 and there is no doubt that all pressure welds belong to systems that are subjected to hydro-static after construction. But my question here, after adding the non-pressure component weld to the outer periphery of the hydrotested system, it is not indicated that the system is to be retested under this code B31.4
However, in accordance with clause 437.1 (b), the retesting requirement is only stated when a leak occurs in the section of the pipe or parts of the components need to be repaired or replaced. Here there is no related topic about the addition of non-pressure components.

 

[QC7]

Hi 1503-44 ,

Noted your comments. But my query is here, after adding the non-pressure component weld to the outer periphery of the hydrotested system, it is not indicated that the system is to be retested under this code B31.4.
Similar like UG99 of Section VIII of the ASME, B31.4 is not restricted to hydrostatic testing without completion of all fabrication {UG-99(a)(1)}.

 

[1503-44]

If not a pressure containing part, my opinion is that retest is not required.
However neither do I believe that indiscriminate welding is allowed on the periphery of pressure containing parts. As the following subsections will suggest, under Repairs, there can be a fine line drawn between non-pressure containing components and welding those items to pressure containing components. Welding pressure containing parts to pressure containing parts is not allowed, therefore I believe welding non pressure containing parts would at least be discouraged. However, if you control the welding of non-pressure containing items to pressure containing parts according to the code and do not adversely affect the properties of the pressure containing components and inspect them accordingly, IMnly, no further testing would be necessary. Non the less, some engineering judgement should be exercised considering the specifics of what it is you are welding on to the pipe, what pipe you are welding to, whether the part is under pressure, or high stress, the location of the part within the system, etc. In other words, I would not favour this, if it might approach something like doing a a hot tap.

451.6.1 Repair
Sub g
451.6.2.9 (d)

 

[QC7]

Hi 1503-44,

I also do not agree with any welding on the outer surface of the hydro tested system. However, if the fabrication team wants to add non-pressure components (saddle support, xxxx, etc.) to the hydro tested system by welding due to incorrect production fabrication planning, then I would like to change this type of sequence by showing the code requirement (here construction code is B31.4). That is why I am trying to obtain comments according to the code.

 

[1503-44]

Yes. As I said, If not a pressure containing part, my opinion is that retest is not required.
Just be careful. Use full encirclement and remember, one arc burn and you're into cutout and retest territory.