Hydrostatic test pressure ambiguity in API 5CT

[metboss]

Hello,

My question is related to API 5CT (9th edition) code interpretation:

CASE STUDY:

The Tubing details are as below
Material Grade T-95 (yield strength = 95,000 psi, Size: 2-7/8", Wall thickness =0.217"

As per API 5CT clause 10.12.3, the formula being given for hydrostatic test pressure calculation as: p= (2 x f x YSmin x t ) /D

P= test pressure to be calculated; f= factor of safety (0.8 for T-95); YSmin = 95,000 psi; t=0.217" , D=2.875"

Now, calculated test pressure, P= 11,472 psi ( rounded to 11,500 psi )

However, in the same clause (API 5CT clause 10.12.3), it’s been mentioned as “ maximum test pressure shall be limited to 10,000 psi ”.

Why such contradiction between two values ( 11,500 psi V/S 10,000 psi) ?

Which one should be chosen (11,500 psi or 10,000 psi) when we conduct pressure test?

Regards

 

[metboss]

Hi all,

Can anyone helm me out in answering my query ?

Regards

 

[EdStainless]

Because 10ksi is a common max pressure for equipment.
And the added stress from the higher pressure is not significant.
Most Code requirements have similar rules, though often they also add 'unless higher pressures are agreed to'.


= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[metengr]

The way I read this section is that the calculated pressure value is used unless the calculated pressure exceeds 10Ksi. So, It would appear the equation for test pressure provides more conservative test pressures below 10 Ksi. So, your max value is 10 Ksi.

 

[metboss]

Thanks Ed and metengrs for your prompt feedback.