For the proposed scenario, the pump comes with a gland water seal to prevent loss of containment for a flammable fluid.
In this case, do we need to consider gland water seal pressure for verification of nozzle loadings (especially thrust) and/or flange leakage?
Because this pressure is substantially higher, if considered, it will result in higher pump loadings and possibly, fail the flange leak verification.
While I can see this as a justified upset condition for a nuclear application, I’m unsure the same applies to a petrochemical plant.

gaboinex,

Most gland water connections are tubing or small pipe sizes. The pump's inlet and outlet piping sizes would be much larger in size and dominate the loads on the pump. It would be difficult to conceive an installation where the gland water or seal flush piping would cause distortion of pump casing or instability of pump base.

Richard,

Thank you for the answer.
I agree with you fully; unfortunately my client doesn't!
The relative small flow rates through the gland water tubing & hose (flex coupling to pump seal) only account for a longer time to build up the pressure inside the piping system in an upset condition.
Hydraulic loss arguments along with supplementary I&C on the gland water circuit were rejected as well.
In this case, installing a PSV (set @ design pressure +10%) in the piping may be the only escape.

gabionex,

Perhaps I mis-understand the concerns of your client. The loads of thermal expansion of piping were what I had thought were the issue. It appears that there is an over-pressure concern with the gland flush.

If the pump is shutdown and blocked in with suction and discharge valves, then the gland flush water could continue to be pressurized and allow pressure into the pump casing from any small leak of the gland seal. If the gland flush water pressure is greater than the pump casing pressure limit, then pump casing could certainly rupture.

If the pump flange connections are subjected to a pressure where the flange joint and gasket might leak, then that is another scenario of possible less concern. I think the gland seal flush water pressure would normally be regulated to a small 20 to 30 psi pressure greater than the normal inlet pressure of pump. There would then be little concern for flange leakage (of gland flush water) beyond normal service conditions. A relief valve for the gland seal flush could be an extra measure of protection along with a pressure regulator for the gland flush water.