ASME hydrotest pressure

By fschweighardt (***)

Date 04-20-2018 14:04

Which ASME Code?
B31.3 for process piping says 150% of MAWP

By Joey

Date 04-24-2018 03:33

As you mentioned "minimum test pressure (e.g 1.3 x design pressure). In actual testing, you are at risk of repeating the test if you set the pressure exactly at minimum test pressure, slightly above the min test pressure is safer in case of pressure to drop due to weather temp condition or air bubbles trapped .

By Jamie Hunter (*)

Date 06-04-2018 04:56

Since you are saying 1.3x MAWP I'll make the assumption that you are talking about ASME Sec.VIII Div.1.

ASME Sec.VIII Div.1 says 1.3x MAWP multiplied by the lowest stress ratio. The LSR is the important part. You'll have to do some digging in ASME Sec.II to for LSR's unless it's already known.

1.5x MAWP was changed to 1.3x MAWP in 1998.

This is a very common mistake that many people make. Someone at some point taught them that 1.5x MAWP is what the pressure test pressure shall be and they never went into the code or read far enough to realize that this just purely isn't true.

Even ASME B31.3 and B31.1 make reference to the LSR.

So, unless you're looking to test this to an out of date code, I'd use 1.3x MAWP multiplied by the LSR to keep to the current edition of the code.

By Joey

Date 08-02-2018 10:01

Repair the defects before hydro test.

By mukund2147 Date 08-02-2018 12:31

Repair is not possible at this stage, need alternative to proof that my equipment is safe for operation.

By Joey

Date 08-03-2018 04:42

I assumed you signed a contract for 100% RT per your customer requirements. Defects detected on locations not RT but you cannot repair the defects. You can propose to derate the equipment and compensate the customer or replace the equipment.

By mukund2147 Date 08-04-2018 14:48

Equipment designed as per 0.85 efficiency so no one can ensure the 100% defect free equipment.
Here the hired agency by client stretching the issue by doing RT on other spot.
How we can counter this issue to justify the work we did.

By Joey

Date 08-06-2018 02:25

I guess this problem arises due to non existence of approved "Inspection and Test Plan" to be used prior to start of the project.
The locations of welds and the points at which they are to be examined by spot radiography shall be selected or approved by the
Inspector.

Check if you have a prior agreement with your customer that a 3rd party will be engaged to do RT on other spots not tested at the shop. If nothing, the cost incurred should be shouldered by your customer. Otherwise, you can say to your boss that this is charge to experience.

By TimGary (****)

Date 08-03-2018 14:25

Generally speaking...

The purpose of RT is to find defects that will promote failures. These defects may be cracks, or conditions that will lead to high cracking potential when exposed to fatigue cycles.
The purpose of initial hydrotest is to validate design values and leak testing. This does nothing to prove that a weldment will not fail during normal use, or after the initiation of fatigue cycles.
Reducing max pressure limits may or may not reduce fatigue resistance and associated crack propagation.
If I were a Customer, I would not accept a vessel with known defects, as I would then be accepting liability for that decision.
When fabricators gamble with weld quality, they often lose.

Tim

By Shane Feder (****)

Date 08-30-2018 06:11

If a client requires a purchased item to be 100% defect free they must stipulate it in the contract documents - eg. 100% volumetric inspection required (and pay the additional costs associated with this).
You cannot stipulate 5% testing (or spot testing) and expect the same level of quality.

By TimGary (****)

Date 08-30-2018 19:34

Disagree...

If a job is contracted to be welded in accordance with a given code or spec, that applies to 100% of welds, unless otherwise specified.
Performing spot check NDE on a percentage of randomly selected welds is a time/money saving short cut that reduces the cost of 100% inspection, provided that all randomly selected NDE checks validate compliant welds. If defects are found, the percentage increases. If defects continue to be found, 100% NDE validation, before and after rework, is necessary.

Granted, this process should be spelled out in an initial contract attached Inspection and Testing Plan. Not spelling it out and having these things agreed to be all parties before the job starts leads to problems down the road.
However, if the Customer can provide NDE reports that a supposedly code compliant job contains defects, I feel that they have the ammunition they need to win a court case.

Tim

By Shane Feder (****)

Date 08-30-2018 22:33

Tim,
Not sure if it is applicable to ASME VIII (will have a look this morning) but this is from B31.3

"Random or spot examination will not ensure a fabrication product
of a prescribed quality level throughout. Items not examined
in a lot of piping represented by such examination may contain
defects that further examination could disclose. Specifically, if all
radiographically disclosable weld defects must be eliminated from
a lot of piping, 100% radiographic examination must be specified."

Walt Sperko has written an excellent piece on this subject on his website

Regards,
Shane

By Shane Feder (****)

Date 08-30-2018 22:49

ASME VIII Div 1 UW-52

Spot radiography in accordance with these rules will not ensure a
fabrication product of predetermined quality level throughout. It
must be realized that an accepted vessel under these spot radiography
rules may still contain defects which might be disclosed on
further examination. If all radiographically disclosed weld defects
must be eliminated from a vessel, then 100% radiography must be
employed.

Regards,
Shane

By TimGary (****)

Date 09-04-2018 22:34

Yup, I hear you Shane, and you're right.

A good I&TP that allows for spot testing will have a rider that states, for example -

Spot RT 10%
If defects found, change to 50%
If more defects found, change to 100% (etc. etc.)

It should also include a provision that if the customer, during receipt inspection VT finds defects that indicate a lack of "thoroughness" (for lack of better words) in the Contractor's work quality / inspection, the Customer has the right to perform additional NDE to determine if the product meets the contract specs. If the Customer finds a lot of defects, hopefully their contract / I&TP will allow them to either reject or repair at the Contractor's expense. This is all too often necessary when shoddy contractors try to push off poor work with falsified inspection reports.

Each case is different, a lot depends on the end use of the products and the severity of potential in service failures, so it all boils down to the job specific I&TP.