Hydrotest exemption for B16.5 flanges
Hydrotest exemption for B16.5 flanges
(OP)
Accordiong to the B16.5, flanges are not required to be hydrotested as part of the manufacturing process. However flanged fittings are not exempt. Is there a specific reason ?





RE: Hydrotest exemption for B16.5 flanges
Not sure where the exemption you mentioned comes from.
Only thing i could think of is flanged fittings where e.g. a WNRF is welded to the fitting, than that weld needs to be tested.
RE: Hydrotest exemption for B16.5 flanges
That's my guess any way.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Hydrotest exemption for B16.5 flanges
RE: Hydrotest exemption for B16.5 flanges
The question from nipra03 comes from:
8.1
Each flanged fitting shall be given a hydrostatic shell test as specified in para 8.3.
8.2
Flanges are not required to be hydrostatically tested
I had no idea of the reason and that is why I didn't respond,
Cheers,
DD
RE: Hydrotest exemption for B16.5 flanges
Just checked the 2013 edt of B16.5, but in that version the references are the other way around, but in principle the same;
RE: Hydrotest exemption for B16.5 flanges
However, what would this sort of counter- specification literally mean, as in many real applications after all the literal "flange" may be contacted little or none at all by the fluid in service? While I guess apparently unlike some politics, I think on the other hand most developers and maintainers of important consensus engineering specifications, e.g. for steel fittings that might be used for quite high pressures and temperatures in important services, generally want their words to mean something at least a little clearer. If there were some sort of dispute and the counter-specifier were to defend his briefly-worded spec with words like, "Well, it is clear I wanted them (the manufacturer or fabricator etc.) to bolt something to the flanges during the hydrotest like will be done in the field", this begs further questions. What kind of sealing mechanisms or gaskets are to be used in this Shop test (there are perhaps hundreds of different gasketing/test sealing types out there), and must the gaskets be new for testing of every flange, or can they be re-used? What kinds of bolts or studs? How many bolts or studs must be inserted? Must the bolts or studs be new for every test? How must the bolts be lubricated or non-lubricated? What means are to be used for tensioning or torquing bolting, how shouold the tensioning be measured, and in what pattern/procedure etc? What QA stuff must be recorded and/or maintained for all this, and for how long? The list and complexity/cost of interpretations goes on and on, and who knows in the end may bear little resemblance to where/how the flange may be used in the actual piping system.
I do not really otherwise know why the writers/maintainers of this particular standard in the fashion they have even bothered to comb this particular seemingly somewhat negative frog hair in the fashion they did (that I believe could have elicited the OP's reasonably honest question); however, if a fitting manufacture absolutely must bolt something individually to each and every flange of each and every fitting, then connect filling and pressurizing hoses, fill and pressurize same (it should be realized in effect having to build all these "mini-pipelines", before they are actually again assembled and tested in the field!) according to some specifier's detailed answer to all of these questions, it should be understood this would be extremely labor-intensive and time-consuming for a manufacturer in at least the developed/modern world, could require substantial time and purchase/coordination of joining materials etc., and I would think this could add greatly to manufacturer's cost and furthermore limit practical availability.
Even if cost and difficulty to manufacturer are perceived no object to a particular buyer, if quick delivery of e.g. common or standard small diameter fittings sitting on a warehouse shelf is needed, what are the chances that those particular fittings were tested exactly how the specifier wanted per answers to the second paragraph above? While I am not familiar with particularly modern smaller diameter steel fitting (near commodity?) manufacture, I wouldn't be surprised if many manufacturers are now for at least most common fitting and valve etc. configurations clearly satisfying at least the present standard verbiage/requirements in clamped specially designed modern hydraulic presses and blocking/mechanized water supply etc., that I would think makes this process much less labor-intensive, quicker and in the end perhaps more efficient for all?
RE: Hydrotest exemption for B16.5 flanges
What may abe more important is whether your pipe design code requires its components to be hydrostatically tested.
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