Hydro test and safety of workers? 2

[AJerry]

Our safety man is having an issue with a contractor on site who wants to work in the area where vessel hydrostatic testing is taking place. Years ago in some documents or code it said that only personal taking part with the hydrostatic test shall be in the area. I said this and the contractor asked what code, as I looked in Section VIII that statement was not there, can anyone help me out?

 

[MTPipeliner]

I don't recall seeing this in a particular code, but it is mentioned in company policies pretty often. Does you company have a hydro-testing procedure or policy?

 

[AJerry]

Yes our company has an Owner user program for pressure equipment, the trouble is this location has been run by 3 different companies over the last 7 years and it maybe in one of the other documents from the last 2 companies that ran this place. Thanks for the help.

 

[chicopee]

It should not be an issue if the test medium is water within the acceptable temperature limits. Water is nearly incompressible and should a leak or rupture take place,water will leak and the pressure within the vessel drop rapidly.
I suppose if the vessel rupture which can happened following fabrication or major repair, metal pieces could be ejected thru the air violently and strike anyone around.
Naturally the contractor should not interfere with the test or work on the vessel undergoing the hydro. until testing is completed.

So a written company safety policy may be in order. get hold of your commercial insurance risk analyst for his opinion.

 

[athomas236]

For your information, in 1967 my company was hydro testing a steam drum for a 660MWe unit. It was about 7ft 6in dia and 72 ft long and failed when at the test pressure of about 3500psig. Sections of the drum weighing over a ton were found in the works car park 50ft away from the test site. Fortunately the failure occured at 4.00am and no one was hurt.

Regards,

athomas236

 

[vesselfab]

HMMMMM

must of had a bunch of trapped air in there.

that's what is dangerous

 

[athomas236]

No air it was January in the UK and canal water was used, hence brittle fracture.

That's why most codes now have a minimum temperature for hydro test.

regards,

athomas236

 

[doct9960]

AJerry,

I received the newsletter below from ABSA last month (only got the time to read it today). There's an article about the dangers of hydrostatic testing. The key thing is not to become complacent and to exercise proper care when conducting pressure tests, even if it's just a hydrotest.

http://www.absa.ca/newsletter/2008-V13-Iss3.pdf

 

[chicopee]

A little late, but in response to brittle fracture, test water must have been colder than the acceptable temperature range specified by NBIC.

 

[mk3223]

Hydrotesting is a dangerous task, especially for the high pressure testing as mentioned above. Also, the temperature of the water for pressure testing depends on the type of material and wall thickness. The minimum pressurized temperature of the materials is indicated in the ASME section VIII.

 

[Sid7]

AJerry

See this link

http://www.hse.gov.uk/research/crr_pdf/1998/crr98168.pdf

Its Pressure Test Safety Contract Research Report from HSE Govt of UK.

Also get hold of Guidance note GS4 (third edition)

http://www.hsebooks.com/Books/produ...&category_name=&product_id=2816&cookie_test=1

It clearly states in para 27
b) the designated test area should be isolated as a no go area and testing should not start until all persons are in safe place;

c) only those persons essential for the operation of the test equipment should be allowed in the vicinity of the test after the pressurisation has begun;

e)....... for safety of testing personnel it may be necessary to consider remote viewing procedures rather than close physical examination;

f)unauthorised persons should not be allowed to approach the pressure equipment untill it has been de-pressurised and vented...

Please note that these are UK Govt HSE guidance notes and the language is "should", "may".

The codes are for "safety" and same time wont be dictating the procedures. If its in your company standard procedures that will make your life easy.

furthermore I second chicopee's statement "get hold of your commercial insurance risk analyst for his opinion."

I doubt if the insurer would be much excited to have non essential people working around the pressure test equipment while testing!

Good luck dealing with contractor aka 'Marlboro Men'


Siddharth
These are my personal views/opinions and not of my employer's.

 

[Sid7]

The Guidance Note GS4(third Edition)

This guidance is issued by Health and Safety Executive. Following the guidance is not compulsory and you are free to take other action. But if you do follow the guidance you will normally be doing enough to comply with the law. Health and safety inspectors seek to secure compliance with the law and may refer to this guidance as illustrating good practice.

cheers.

Siddharth
These are my personal views/opinions and not of my employer's.

 

[RussTee]

AJerry,

The statement that you're looking for is not found in ASME Section VIII, but in API RP 572, Section 10.8.2. The document states:

"When conducting hydrostatic or pneumatic pressure tests, it is a good safety practice for all personnel not connected with the tests to remain away from the area until the test is completed and the pressure is released. The number of inspection personnel in the area should be limited to the number necessary to run the test."

I hope this helps.

Regards,

RussTee

 

[MJCronin]

To all....

Hydrostatic testing can also be scheduled for times when there are no workers in the area.

It is not unusual for the test, which usually takes a few hours, to be scheduled on an off-shift

-MJC

 

[PVinspector]

Athomas236 wrote:
"No air it was January in the UK and canal water was used, hence brittle fracture."

I guess the laws of physics must have been repealed in 1967. because if it was filled with water and no air was compressed, where did the energy come from that moved 2000 lb. parts 50 feet come from?

There was air trapped, or it didn't happen.

 

[athomas236]

PV Inspector,

It happened, I was at uni at the time so only had the briefest of reports. All I know is what I have said but BS1113 did introduce a minimum temperature for hydro testing shortly after.

Regards,

athomas236

 

[JoeTank]

PVInspector. I don't see a problem with a big chunk of vessel being hurrled 50 feet during a brittle fracture even if the vessel is filled with water. It's not unusual to have to gather up a few dispalced parts after such an event.

Joe Tank

 

[PVinspector]

OK, not trying to be argumentative just before Thanksgiving , but with an essentially incompressible fluid and no air trapped, exactly what would propel a ton of steel 50 feet? Bad juju?

I have witnessed quite a few burst tests when working with a testing agency, and when no air is present, there is a bang, a splash a fluid, and that is it, even when ripping holes in substantial steel plate at 5000 psi.

I did not say it didn't happen, I am just saying if there was no air compressed, what caused it? Still have not heard any suggestions compatible with the laws of physics.

 

[JoeTank]

PVInspector,
Obviously, it was bad juju. I have seen several brittle fracture events after tests, each conducted with care to eliminate air being trapped. In several cases, the splash ocurred, but a part of the vessel was ejected a short distance from the vessel. Not a 2000# chunk going 50 feet though. If it came off of the top of athomas' vessel, I could accept the 50ft toss.

Joe Tank