NDT and pressure tests for pipes in mill

[engahmedbahgat]

Hello ,

I would like to ask about NDT and pressure tests for pipes in mill, do these tests executed for all pipes lot or for sample (as destructive tests)

thank you in advance

 

[LittleInch]

Normally yes, all pipes are pressure tested to 90% SMYS for about 10 seconds.

Other NDT, e.g. weld testing is sometimes less comprehensive, but often can be 100% UT inspection as well.

The other tests (bend tests etc are from a sample where a part of the pipe is cut off and tested ( often 1 in 50 pipe or so) You don't normally lose an entire pipe to a destructive test.

Why do you ask?

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

 

[bimr]

It depends on the manufacturer and what the purchaser specifies:

"Purchaser may specify NDE in lieu of hydrostatic test or neither."

http://usstubular.com/standard-and-line-steel-pipe/a106-seamless-carbon-steel-pipe

 

[weldstan]

The mill will perform the tests as defined in the material specification and any added Purchaser requirements.

 

[rconner]

It has always taken significant capital (in the form of equipment and water supply/treatment etc) and working/operating time and expense to reputably hydrotest (particularly as pipe sizes get larger) all pipes in factories. While it can certainly be argued a hydrostatic test, particularly at 75-90% of Y.S. of all pipes before they are shipped and exposed to lesser pressures in the field is a pretty darn good "inspector" or proof test with real value to the Owner, some contemporary pipe material manufacturers and standards folks have in recent years collaborated imn efforts to minimize same. The spec verbiage quoted by bimr may be more straightforward (and honest?) than some, e.g. see following other examples from AWWA standards some of which that may kind of make it sound like all pipes are tested (i.e. designed to sell?), when in reality they may well not be?

1. From AWWA C950 for composite (like fiberglass) pipes, "5.1.2.1 Hydrostatic leak tests. Unless otherwise agreed on by the purchaser and supplier, the manufacturer shall perform hydrostatic leak tests to all pipe sizes 1 in. through 96 in. (25 mm through 2,400 mm). For sizes greater than
96 in. (2,400 mm), the frequency of hydrostatic leak tests shall be as agreed on by
the manufacturer and purchaser..." and
"5.1.2.1.1 A length of pipe, when tested, shall be placed in a hydrostatic pressure test machine that seals the ends of the pipe..."
[Notice that the first passage says "to all pipe sizes", not all pipes; also, the latter quoted passage just says "A" (meaning one?), does not even require that any full-length pipes be tested, nor does it even require that the tested pipes be representative of the lot in either the structural or strength of materials senses. For various reasons very short pipes can in many cases be more cheaply teste,d and can also more readily pass high pressure tests than very short pipes.]
2. From AWWA C906 for polyethylene pipes, " 5.4.8 Five-second pressure test. This test shall be performed at least once per production run. The ring-tensile strength test (Sec. 4.3.5) or the quick-burst test (Sec. 4.3.6) may be substituted for this test..."
[In other words e.g. only one polyethylene pipe, or no pipe in the case a short ring tensile sample is cut and tested, per routine production run may actually be hydrostatically tested, and again there is no requirement that full-length as opposed to very short pipes be tested, nor that the tests even be specifically representative of performance/behavior of actual full-length pipes.]

All have a good weekend.

 

[rconner]

Oops, in my bracketed commentary on the quotations of item 1, I of course meant to say, "For various reasons very short pipes can in many cases be more cheaply tested and can also more readily pass high pressure tests than full length pipes."