Dual Stencilling of API 5L Pipe (i.e. X42/X52)

API X grade shows the minimum yield strength of particular grade. For instance X42 means 42000psi yield strength. Dual marking for different grades are some time acceptable for example ASTM A106 Grade B and API 5L grade. Both of have same strength but different requirement.

Adeel Ahmad

It is a controvercial issue, and I am not sure it is yet resolved. API as on now was a bit ambiguous in this matter, but now woken up. The revision of the standards may be on card. Wait till then.

http://napca.com/webfiles/2009_Workshop/NAPCA_-_Workshop_-_2009_-_Bob_Wise_Presentation.pdf

Sorry, just a bit outdated.

It is resolved now, dual marking is permitted if it meets the requirement of both the codes

http://www.api.org/meetings/topics/pipeline/upload/Ed_Baniak_Technical.pdf

look at page 47.

The strength requirements for X42 are min. YS: 42,000 psi and min. UTS 60,000 psi, for X52 they are 52,000 and 66,000 psi. Thus it isn't exactly difficult to have a pipe which meets both requirements, and X46 (46,000 and 63,000 psi) as well! In fact, you could go up to X70 and still meet the requirements for the lower grades.

If you are working to PSL2, so long as the UTS doesn't exceed 110,000 psi and the elongation requirement is met, you could still use X70 pipe and meet X42 standards.

Regards,

Owen.

You will find more variation allowed within a grade than between the grades at their nominals. Thus you can look forward to seeing much more of this in the future.

Usually pipe is dual stenciled at the request of a reseller (i.e. distributor) so they can sell either requirement out of inventory. Some end-users will request X-42 and actually not allow a substitution of X-52 out of fear the field welding and/or field bending specification was written for X-42. Having the pipe dual stencilled allows the seller to guarantee the buyer that even though the pipe is strong enough for X-52, it still falls under the max strength levels for API X-42. BTW, pipe will sometimes actually be tripled stencilled with Grade B added as well although this requires a little tighter window for the yield strength.