PED IMPACT TEST REQUIREMENTS

[Graybags]

Hi,

Is there a need to impact test Nickel Aluminium bronze material to satisfy the PED?

Annex 1 sestion 7.5 states that a steel is sufficiently ductile if its bending rupture energy measured on an OSO V tset-piece is no less than 27J at a temperature not greater than 20 deg C but not higher than the lowest scheduled operating temperature.

Guideline 7/17 reads as follows:-

Q) Shall a steel grade selected for a pressurized part always have specified impact properties?

A) Yes, the only exception is ductile materials which are not subject to ductile/brittle transition at the foreseeable conditions the equipment will be exposed to.

The component i'm designing is a pressurized valve body with a minimum working temperature of -20 deg f.

Is nickel aluminium bronze sufficiently ductile to not exhibit ductile/brittle transition at this temperature?

I'm really scratching my head with this one. I asked the same question to my notified body months ago and cannot get an answer from them.

Any advice would be very appreciated.

Regards,

Graham

 

[stanweld]

The regulations that you have quoted apply to steels - not copper alloys.

 

[Graybags]

Thanks for your response stanweld.

This is my argument exactly for not impact testing copper alloys for -20 deg F service. However, on a recent PED audit, the notified body rep. highlighted to my collegue that the copper alloys should be tested. Is he making his own directive up?

I have since spoken to the guy who rubber stamps our cat 3 and above PMA's and cannot get an answer on the subject of impact testing copper alloys.

Thanks again in advance,

graham

 

[lostsailor]

Graham,
Over the past several years one of my clients has been working on jobs containing nonferrous alloys with my involvement as the NB inspector. At the time the contracts were let, there was no concrete data regarding nonferrous alloys and impact testing in the PED. What wound up happening was a flurry of emails going back and forth resulting in a client transmittal indicating lack of meaningful data resulting from impact testing which was then endorsed by the engineer reviewing the technical file. Supporting metallurgical and engineering references were supplied. Hope this helps.
Regards,
RLS