Code clash? 2

[JaseSymons]

Hi all
I'm working (in UK) on a sulphur dioxide line(<10 bar) which the PED and client line lists classify as SEP. The client line specs however specify ASME 31.3 and class the pipe as Cat 'D' while under ASME I believe SO2 would mean a Cat 'M' classification. I'm confused. Which classification takes precedent? Would Sound Engineering Practice be to use Cat 'M' section of Code?

 

[XL83NL]

If you're the manufacturer (as laid down in the PED) of the piping system that falls under the PED, you're the one responsible for determining the correct category for the piping system. Not the client.

1) ASME does not classify a fluid service as cat D, N(ormal) or M. It only specifies the requirements for fluid services.
Obviously, one can easily determine that e.g. H2S is highly unlikely to be categorized as cat. D fluid service, as H2S cannot be classified as 'non-flammable, non-toxic an not damaging to human tissues as defined in 300.2". However, in reviewing para 300 of B31.3, and reading the Owner's responsibilities, you can see the owner may even classify water as cat. M fluid service, as it is his responsibility. Eventually, it's up to the Owner.

2) In determining what prevails and comes first, a rule of thumb I typically use;
i) find out your jurisdictional requirements; they come first.
ii) determine client requirements, typically spelled out in the contract. First off; the design code. Second; additional specifications

3) If nothing is specified, apply sound engineering practice and RAGAGEP. This is most easily done by applying ASME B31.3 as your design code, or EN 13480.

 

[Duwe6]

what XL83NL said, only more so. It is impossible that SO2 is a Category D fluid.

As to whether it is Category M, it depends on concentration. Will a few breaths of it cause "permanent harm and irreparable damage"? That is the typical criteria for deciding between 'Normal' and 'Category M'. And yes, the owner needs to be part of this decision. If it was my system, it wouldn't take too high a concentration before I had Category M invoked. The 100% X-ray/UT would provide me a lot of comfort and confidence.

 

[OSIRIS7]

The PED is leading because it is a directive which has been implemented in the law of the UK too.

However PED classifies as SEP, it is up to the manufacturer (in terms of PED, not nessecary the company that fysically produced the equipment) to deliver safe and sound equipment. One of the possibilities to show to the client that you are complying to good engineering is by following a design code. If you choose ASME, that is just fine. PED is leading however.

1) PED
2) Design code
3) Client requirements

As you are in the UK you have several standards at your disposal like EN 13480, ASME and BS. Also other accepted standards like Dutch Rules for Pressure vessels or AD Merkblätter should be acceptable. When the client requires a specific design code, for instance because the entire factory is build to that code, and you have experience with this code, I would suggest to follow it. If not, then I suggest to communicate with the client.