AWWA C200 Pipe Welding

[JoelTXCive]

I have an existing 60" water pipe that was fabricated and installed in ~1986. The pipe is an emergency overflow line for a small stream that sits empty 99% of the time. But every now and then we get a 100yr+ storm event and the pipe carries a gravity flow.

Per the original construction plans, the spirally welded pipe was fabricated in accordance to AWWA Standard C200-80. That is all I know about the existing pipe, other than the interior is coated with coal tar epoxy and the exterior is epoxy painted.

We need to extend this pipe by about 11ft. The pipe is fully supported along the length of the extension. I specified that the contractor should match existing material specifications and that the welded extension be welded in accordance to AWWA C206-17 for field welding.

The contractor has informed us that an 11ft length of pipe is too short to be spirally welded. Instead, they would like to use a straight seam welded pipe for the 11ft extension.

They have provided the following material spec:

"60" OD x .500 wall x 318.03lb steel casing. Pipe will have a 36ksi minimum yield strength and will meet or exceed the physical properties of A252-Grade 2. The pipe will be of leak proof construction and beveled for welding"

My questions are:

1) How can I do my due diligence that the proposed extension material is acceptable?

2) Assuming the material is acceptable, then is calling out the C206-17 weld standard acceptable? (I have a standard AWWA C206 weld details in the plans)

Thank you in advance!

 

[jhnblgr]

Install the pipe, embed the joint in concrete and then have a slip liner installed inside the pipe.

 

[JStephen]

So far as I know, spiral-welded pipe has been viewed as a cheaper option that has not always been viewed as equal to regular pipe. So conventional mill pipe should be fine, or fabbed from plate by local vessel fabricator or steel fabricator should be fine.
I'm not familiar with C206. I would assume it refers back either to AWS D1.1 or to ASME Section IX for most weld details (more likely the latter). I'm not aware of a lot of reason to prefer one over the other, other than using what the contractor already has weld & welder qualifications for.
Minor issue, a lot of the C200 pipe is fabricated so that nominal size is the ID, not the OD, so the existing 60" pipe may be 60" ID. If the pieces will be butted together, measure that existing pipe first.
C200 may include hydrostatic testing requirements that would be difficult to do on a single short piece like that, so it may not be reasonable to fully comply with C200.

 

[HTURKAK]

A profile of the pl would be more helpful to see the problem. As per the info. provided by OP , the extended portion will also be gravity flow .
I would consider other jointing and pl materials and avoid welding . Two options ;

- Use VJ coupling and in this case the extension pipe could be steel, GRP, PEH .
- Provide a manhole and so , the extension pipe could be R.Concrete, steel, GRP, PEH .

I will suggest also , delete this thread and post at piping group to get better responds.

 

[goutam_freelance]

I have used these types of pipes in large numbers for power plant circulating water systems. The max pipe OD was more than 60 in and the piping was fabricated in local shops using SAW.

The most difficult task was to hydro-test the spools for which a special rig was erected at the site. For a single spool, it will be costly hence radiography can be done as an alternative Refer AWWA C 206 C clause 5.2.2-Testing of special sections. However, the hydro test can also be done using weld-on heads or blind flanges, which need to be removed subsequently by cutting.

The final welded connection to the existing pipe can again be tested using radiography.