5,000 psi working pressure equipment
used for 6,500 psi service.
I have heard that I can use 5,000
psi working pressure equipment for 6,500 psi service. Is this true? .
API Spec 6A and
16A 5,000 psi
nominal working pressure connectors using 60K yield strength API
specified materials were originally designed for, and tested originally
to 10,000 psi test pressure. With the publication of API Spec 6A 19th
Edition and API Spec 16A 3rd Edition, API introduced a uniform
requirement for designing and testing all equipment, 5,000 psi and higher
working pressure, for a test pressure of 1.5 times rated working
pressure. This resulted in a reduced design requirement for 5,000 psi working
The new reduced test pressure
meant that 5,000 psi working pressure equipment, built to older design
criteria and tested to 10,000 psi, could theoretically be rated to 6,666
psi, rounded to 6,500 psi, and have consistency with current
design requirement stress allowables.
Although API has made no statement
about this matter, many operators have adopted the practice of using
5,000 psi nominal working pressure equipment manufactured to API 6A 17th
and API 16A 2nd and earlier editions of these specifications for service
up to 6,500 psi.
Operators should only risk this
non-standard practice if they confirm with equipment manufacturers that
all 5,000 psi nominal equipment in an assembly was originally made to
the 10,000 psi test requirements, and the manufacturers have, or would
make certification as such. Manufacturers should be asked specifically
if their valve closure mechanisms are suitable for 6,500 psi service.
Equipment manufactured to API 6A
19th Edition requirements, and tested to 7,500 psi should not be
up-rated to 6,500 psi working pressure without the specific equipment
manufacturer confirming equipment design criteria, and re-test to 10,000
Operators should not assume that existing 5,000 psi working pressure
equipment can simply be tested to 10,000 psi and then used as 6,500 psi
working pressure simply because it did not fail on test.