ARE THERE GUIDELINES ON HAMMER PEENING FOR LEAK MITIGATION PURPOSES? 5

[Bambie]

At my plant, peening is used to temporarily stop leaks on pressurized metal items.

This includes the following applications:

- closing through-wall cracks & pinholes on pipes
- closing gaps between mating pipe flanges or body/bonnet flanges on valves
- sealing interface gaps between tongue and channel clamps and flanges, and
- closing perimeter seals on bolted sealant injected enclosures.

There is plenty of information on water, laser, UT and shot peening for fatigue enhancement or forming purposes out there, but very little on pneumatic/chisel/hammer peening on pressurized items.

Leak Stopping Service providers that I have approached appear to consider this practice to be a trade secret.

Has anyone encountered guidelines (besides EPRI NP-6523-D) with specific constraints for extent of peening based on materials and applications with a focus on worker safety?

 

[Bambie]

I think the only way I can extract technically based and balanced opinions from this forum is to 'parse out peening' so to speak.

Lets first agree that every application of peening:

- is designated a temporary, non-standard method to mitigate leaks when a standard methods are not possible or effective on pressurized components,
- receives assessment and approval by Plant Engineering following examinations to determine the nature of the pressure retaining degradation and the remaining structural integrity such local wall thickness measurements, checks for cracking, pitting, corrosion etc.
- installation is documented and a removal date is agreed to with the regulators
- is never a 'stand-alone repair' to pressure retaining components, but used like a gasket to improve sealing of the pressure retaining, sealant injected extension designed to mitigate inventory loss
- is applied by a licenced specialist with recognized expertise in the art of manual and pneumatic or electric hammer peening on pressure retaining materials.

Let me elaborate on the examples in my 'introduction to peening'

1) "closing through-wall cracks & pinholes on pipes"

Peening permits the safe installation of a sealant injected enclosure that would otherwise have to be bolted together while the technicians play dodge ball with jets of steam or chemicals flying about their heads.

2) "closing gaps between mating pipe flanges or body/bonnet flanges on valves"

The fasteners in any leaking flanged connection are checked for preload and either UT'd to confirm all are crack free or replaced one by one (with clamps assisting).
Calculations must confirm that fastener stress remains within code allowables when system pressure is extended to the flange perimeter before sealant retaining rods are inserted between flange gaps and the flange edges are peened over to retain the rod, which acts like a dam to prevent sealant egress.
Torque checks and adjustment are required following each peening pass to ensure fasteners are not picking up load from wedging action.
Peening passes are limited to three after which Plant Engineering approval is required.

3) "sealing interface gaps between tongue and channel clamps and flanges"

Grooves or lips are machined into tongue and channel clamps which, when peened into the rough casting and/or corroded external surface of the pressure retaining material, will impart a tight seal for retaining sealant.
The same constraints on peening described in 2) are applied.

4) "closing perimeter seals on bolted sealant injected enclosures"

Grooves or lips are machined into the external perimeter sealing edges of enclosures to assist the internal rope packing to prevent the egress of sealant and process fluid.

I hope this brief introduction has explained the importance that peening plays in leak mitigation (not repair of pressure retaining material) and made it possible for a 'discussion' about why this secretive but extremely useful practice has not been recognized and guidelines produced to assist with its safe applications.

 

[mfgenggear]

@Bambie
you are hard headed, from being in business for 40 years as others have stated, do not guess or do not allow repairs, that compromise safety of the product.
let me tell you what can and has happened,
. if any one gets hurt or killed the FBI will shut down the plant, every ones computers and records will be confiscated.
. You and the company will be under investigation, if illegal repairs were conducted,
you may get fined and go to prison.

does that sugar coat it enough. seen it happen over the years were fraud, illegal repairs, & more you name it.
when people stamp their names on those certifications or paper work it is a legal document.
with your name on it.

 

There's an interesting website I visit from time to time for their very informative investigative reports. CSB

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[mfgenggear]

@ironic metallurgist unbelievable of the incidents at the CSB , thanks for that link.

 

[mfgenggear]

@WKTaylor thanks for over the years wisdom, and sharing knowledge.

 

[LittleInch]

this secretive but extremely useful practice has not been recognized and guidelines produced to assist with its safe applications

Errr, well this puts it in a nutshell. It's a secretive practice and no guideline have been produced because the whole thing is fundamentally unsafe. Somehow, somewhere, your plant has come to accept this as "normal" whereas just about everywhere else this is seen as a practice which should not be encouraged.

Working to repair system in a live condition is extremely hazardous and should only be attempted in very special circumstances. The risk to personnel and equipment is high and potential for escalation high.

I don't know your role in this establishment but like mfgengear says - my advice would be not tho have your signature anywhere near such practices. If the regulator actually permits this to continue then I can only shake my head in disbelief.

All IMHO.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Bambie]

I am beginning to think that peening may very well be Engineering's COVID-19!

 

To quote somebody whose name I can't recall, "just say no"

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[0707]

Bambie

Is it possible to know in what type of industry do you work?

Good luck

luis

 

[Bambie]

0707

Good heavens no, mfgenggear might report us to the authorities !

 

[IRstuff]

mfgenggear might report us to the authorities

Given what you insist on doing, is that really a bad thing? You've been told that it's not safe, but you seem to reject that out of hand.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[mfgenggear]

Good heavens no, mfgenggear might report us to the authorities !
@bambie I don't know what you mean
Take it as constructive advice.
Take care

 

[WKTaylor]

Just taking 'a SWAG' here...

Bambie, guessing you are 'probably' working at non-US/Canada/EU location...

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[IRstuff]

Their profile puts them in Ontario

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

Time to draw a line under this I would say.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."