Boiler hydrotest

[alizali]

dear
for a water tube boiler that works over 10 years, without any welding after hydro test with 1.5 times MAWP
do we need to test with this pressure every year in inspection?
if yes does it safe?
if no what is the code or standard for this situation?
in another topic i found this case referes to NBIC Refernce NB-23 Part 2 Para. 4.3.1.2
but i can not find it
can anyone have any idea?

 

[metengr]

The requirement for annual pressure testing is not in the NBIC. This is typically a requirement either by the local regulatory body or your insurance carrier. I do not agree with this approach unless the boiler is small and cannot be inspected visually or with use of nondestructive testing. Pressure testing can result in other problems with watertube boilers, such as corrosion and brittle fracture of larger pressure retaining components. You need to carefully evaluate this type of inspection method versus other approaches.

 

[alizali]

the boiler is 15 ton steam producer per hour.
the steam drum, mud drum and fire box is reachable.
the tubes in firebox is tested as fallow
1. thickness measurement that tube are between 2.5 and 3 mm with no corrosion history
2. hardness test that all tubes are under 200HB.
the first hydro-test pressure was 21 bar
it works for more than 15 years
so now from insurance company force us to hydro-test the boiler.
now we are looking for a code or standard to clear the pressure for hydro-test?
we believe test with 21 bar is not Intellectual.

 

[metengr]

Why are they requesting to hydro the boiler? You can recommend nondestructive testing (MT, UT) and visual examination to determine the health of the boiler pressure retaining items.

Hydrostatic testing is only real time and will tell you nothing about future reliability or condition assessment other than if you have current gross defects or large defects which can be fixed and the boiler returned to service.

 

[alizali]

dear metengr
we belive in the same way and so we never hydrotest boiler before.
but the insurance company and our SGS inspection (for ISO 9001 licence) force us to do it.
we are looking for a code or standard that tell us
1. we do not need to hydro test the boiler
2. if we have to, what is the test pressure?

 

[metengr]

If you are forced into this, I would use the NBIC requirements for pressure testing with water in Part 3 (Repairs and Alterations) at operating pressure and not 1.5X MAWP or design pressure.

 

[alizali]

could you give me this NBIC.
i can not find it anywhere
at least a scan of this page that told testing with working pressure is allowed
thank you

 

[metengr]

Here is an excerpt from Part 2, 4.3.1.2. I want to caution you that you have a choice on test pressure up to 1.5X design pressure. I would select up to 90% of operating pressure to ensure no damage to pressure relief devices. Removing these devices for higher pressure can result in damage and adds cost for no additional benefit.

Here is the excerpt from Part 2 of the NBIC


4.3.1.2 LIQUID PRESSURE TESTING
Test pressure should be selected or adjusted in agreement between the Inspector and Owner-user.
The liquid test pressure shall not exceed the lesser of 150% of MAWP or test pressure established by the
original code of construction.
When a pressure relief device is left in place, test pressure should not exceed 90% of set pressure of the lowest
setting pressure relief device on the pressure-retaining item to avoid damage to pressure relief devices.
During a liquid pressure test where test pressure will exceed 90% of set pressure of a pressure relief device,
the device shall be removed whenever possible. If removal of valve-type devices is not possible or practical,
a spindle restraint such as a gag may be used provided that the valve manufacturer’s instructions and recommendations are followed. Extreme caution should be employed to ensure only enough force is applied
to contain pressure. Excessive mechanical force applied to the spindle restraint may result in damage to the
seat and/or spindle and may interfere with proper operation of the valve. The spindle restraint shall be removed
following the test.

The organization that performs the liquid pressure test and applies a spindle restraint shall attach a metal tag
that identifies the organization with the date the work was performed to the pressure relieving device. If the
seal was broken, the organization shall reseal the adjustment housing with a seal that identifies the responsible
organization. The process shall be acceptable to the Jurisdiction where pressure-retaining items are installed.
Metal temperature shall not be more than 120°F (49°C) unless the Owner-user specifies the requirement
for a higher test temperature. If the Owner-user specifies a test temperature higher than 120°F (49°C), then
precautions shall be taken to afford the Inspector close examination without risk of injury.

Hold-time for liquid pressure tests shall be for a minimum of 10 minutes prior to examination by the Inspector.
Test pressure shall be maintained for the time necessary for the Inspector to conduct inspection.

 

[alizali]

thank you very much
very helpfull