HYDROTEST PRESSURE 1

[opinion1055]

Friends,
I have an 8"-Sch80 - A106.B / BFW / 900# line .
The design Pressure for this line = 114 Kg/Cm2 G
The hydrotest pressure (as per spec.) = 171 Kg/Cm2 G


But,from ASME B16.5 flange rating table, maximum pressure for class 900 is 147.75 @ amb temp(60deg c).

So,is this hydrotest pressure @ 171 Kg/Cm2 G feasible ?

opinions awaited.....


thanks in advance

 

[kvbalu2129]

I am assuming that the Flange material is ASTM A105. I think the flange rating of 900# allows hydrotest pressure upto 235 kg/sqcm (Pls check hydrotest temperatures in B16.5). The pipe material needs to be check for stresses developed due to hydrotest pressure. Normally, stresses upto 90% of Yield strength of the material of Piping are acceptable for Hydrotest pressures (ambient temperatures). This I believe is due to the reason that this is an occassional event.

 

[XL83NL]

This has been discussed before;

http://www.eng-tips.com/viewthread.cfm?qid=369092

http://www.eng-tips.com/viewthread.cfm?qid=370381

B16.5, by means of para 2.6, allows a hydrostatic test pressure equal to 1.5 times the flange rating @ ambient, rounded off to the next higher 1 bar.
Assuming a flange acc. B16.5 group 1.1 (table 2-1.1), Cl. 900, the hydrostatic test pressure of the flange is 230 bar (235 kg/cm2)

 

[opinion1055]

Thanking you kvbalu2129 and XL83NL for your swift reply...

My doubt is very well settled....