Hydrotest of FRP piping: Testing pressure? 4

[Eagle_Weld]

Hi all,

Is hydrotest pressure is stated in codes AWWA C950 and AWWA C900 or other for plastic/ non metallic piping?


TQ,

 

[Eagle_Weld]

I am looking for how to determine test pressure of FRP pipes.
AWWA C950 doesn't specify test pressure.
For example B31.3 specify that for Carbon steel pipework, the test pressure is Pt= 1.5 x DP x stress ratio.
Is there a formula applicable for FRP pipeworks??

 

[LittleInch]

Then see what the vendor states in their data sheet or literature.

I found a data sheet from Ameron which states 150% of rated pressure.

I'm fairly sure ISO 14692 requires 1.5 times design pressure (may be less than the pipe rated pressure) or 0.89 times the "qualified Pressure"

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

 

[zdas04]

I've tested a lot of FRP, all to 150%

[bold]David Simpson, PE[/bold]
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[moltenmetal]

Just don't pneumatically test it...but a hydrotest at 150# should be possible- if not, it's likely inadequately safe to use long-term.

 

[Eagle_Weld]

OK 150% of design pressure would be acceptable. But to what code shall I refer to?
What about holding time at that pressure do you think that it will be safe to fix it 30 minutes?

 

[bimr]

American Water Works Association maintains the standards for small and large diameter fiberglass pressure piping in potable water pipelines including:
i. AWWA C950 for Fiberglass Pressure Pipe which outlines general requirements for materials and manufacture.
ii. AWWA M45 Manual of Water Supply Practices which provides information related to design, specification, procurement, installation and understanding of fiberglass pipe.

The AWWA Manual 45 recommends that FRP pressure pipelines be tested after installation but does not provide any test pressures. The lack of more detailed information on field testing in M45 is related to the small amount of FRP used in municipal service. Manufacturers recommend 1½ times the design operating pressure.

 

[Eagle_Weld]

zdas04, what was the holding time when you tested FRP pipes?

TQ

 

[zdas04]

I have done both pneumatic and hydrostatic tests at 150% of design pressure, and the client called for 2 hours. One (pneumatic) was required to hold for 24 hours and I was very glad it was a pneumatic test because the day to night temperature swing on a 5 mile pipeline would certainly have failed a hydrostatic test.

I'll never understand the bias against pneumatic tests, while at the same time being quite OK with using FRP for natural gas service (that is a gas too, by the way). I put my position in a Paper at Engineering.com if you are interested in that discussion.

[bold]David Simpson, PE[/bold]
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[rconner]

You ask a very good question, as it is indeed some odd standards and manuals for frp do not specifically mention any guidance on testing levels for field hydrostatic testing like those of many other materials. I noticed the copy at

http://www.fiberglasstankandpipe.co.../installation-of-large-diameter-buried-pipes/

(that appears to have been updated as late as 2013) e.g. states simply at the very bottom,

"Pressure lines can be tested by pressurizing water at operating levels or higher. " (As an engineer reading this, I have to ask myself the question, "If I take the lower end of this advice and test the project only to the "operating level", when even a little higher surge event occurs, and say at a point a little beyond the normally quite short Contractor's warrantee period, who would be responsible if the pipeline fails?"

While I think it has been around more than sixty years I understand (and as bimr notes) frp has historically been used for only a very small proportion of e.g. significant transmission pipeline works in the USA. I do know however specifically field testing and as many would argue are not at untraditional levels for at least legacy pipes eventually became a quite thorny issue on reportedly the largest frp piping project ever attempted in the USA a few years ago (and even at the time, "purportedly the largest application of fiberglass pipe in the world"). Some of what reportedly transpired is documented in the audit account starting on page 75 of the file at

http://clkrep.lacity.org/onlinedocs/2005/05-2252-s2_rpt_dwp_01-22-08.pdf

. It is thus probably best when all parties know up front exactly how the installed pipe must be field tested, and who is to handle/responsible when it does not pass same.

All have a good weekend.