Hydrotest Pressurization

why need to do pressurize and depressurize properly in hydrotesting?
what are the causes will happen if not done properly?
any technical answers please?

If no pressurize, how to reach a test pressure? and
If no depressurize, how to drain test medium.

Acceptance and procedure to follow codes/spec.

Dear sir,
what i mentioned is ‘‘properly’’…if team is not doing the procedure like 1bar/1min.instead of this they are raising suddenly and decreasing suddenly…what will happen?

I think, It is not an issue.
In case of testing of pipe (SMLS or Welded) or valves are only held at 5-10 seconds, then reduce fastly.
A special notes, you may check in specification.

It also depend on volume of test medium.
Normal design pressure are lower than a min. yield stress. So, there are no issue during pressurize/depressurize (pipe and valves).

IMPORTANT!! inspector should visually inspected at design pressure after holding time and test pressure reduced.

Dear sir, Thankyou.still lit bit confused.please clarify this too.

my design pressure for the pipe is 95 bar.SMYS for the pipe is 360MPA. so in this case if i do pressurize and depressurize improperly anything will happen?

Pressurize properly in order to ensure stabilization pressure test to prevent pressure may be drop during holding time. Normal for pressure vessel 50%,100%. For Piping 25%, 50%,75%, 100%.
Depressurize properly in order to examination leak at design pressure.

dear sir,
thank you.can you explain my last comment also.
design pressure for pipe is 95 bar.smys for pipe is 360MPA.so in this case if i do pressurize and depressurize improperly anything will happen?

it is just for my knowledge only.i am not gonna to test this.

Fast depressurization causes vaccum generetion in pipelines.

Carry out pressurize improperly, pressure test may be drop in during holding time. Depressurize improperly , can’t examination leak at design pressure or more serious cause to deformation for shape as fast depressurization with big volume.

Instruction for your test pakage at design 95 bar


Improperly pressure may be caused deformation,