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Weldolet - Allowable Pressure 2

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MechD

MechD

Mechanical
Jul 5, 2010
12
Hi,

If I am using Bonney Forge Weldolets (specifically manufactured to MSS-SP-97 standards), are pressure calcs required for the fitting?
I have already found the straight pipe allowable pressure & corresponding wall thickness to EN13480-3. Are Weldolets certified to cover the pipe's calculated allowable pressure?

Thanks

(Sorry, new to this site & already posted this thread in Mech Eng - Other topics)
 
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weldos are specified by required minimum working pressure. 2000 psi is a typical spec. Does it have 2000 or another working pressure rating forged onto it?

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
"Being GREEN isn't easy." Kermit[frog]
 
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Thanks BigInch but we're still in the early design stage so haven't bought any weldolets just yet.

Line pressure ranges from 4 - 16 bar. I've already emailed Bonney Forge, asking if they can certify a specific allowable pressure per fitting, or certify that it will match (or exceed) the straight pipe calcs.

Just trying to work out if I need to do calcs, and if so, where do I find Weldolet formulae?!
 
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No, spec the minimum working pressure, let them certify they've furnish something with a higher working pressure than that, and then .... on to the next job.

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
"Being GREEN isn't easy." Kermit[frog]
 
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MechD, to add a bit of additional information.. you don't need to do branch reinforcement calcs, because the weldolet is precertified for a given pressure.

If the branch connection to the pipe was instead fabricated, using say, a welded pad, then yes you would need to do the branch reinforcement calc from the appropriate B31 code.
 
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MechD,
As people had mentioned Weldolets are pressure rated so as long as you specify the weldolet with the correct pressure rating above your pressure then "job's a good one". There is no need to perform calculations as these fitting designs have been proof tested by the fabricator. Branches are integrally reinforced so no calcs required.
 
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Bonney Forge puts out a pretty good catalog at
On page 7 of that catalog you'll find a couple sections which are useful:
HOW TO ORDER BRANCH CONNECTIONS
HOW TO SPECIFY BONNEY FORGE BRANCH CONNECTIONS

See also TEMPERATURE - PRESSURE RATINGS on page 8 and the Engineering Specifications section which begins on page 32. I've often seen excessive welds on weldolets - see the distinction between the "rib" and "weld line" on page 35.

jt
 
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Actually, if you look at MSS SP-97, O-Lets are not actually specified by pressure rating. They are given Class rating which you then correlate to a specific pipe schedule of run and branch pipe. Same situation as for regular threaded and socket welded fittings. The Class 3000 rating is not actually a 3000 psi rating as is commonly assumed (refer to ASME B16.11)
 
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2000 lb O-lets are good to the pressure rating of Sch 80 pipe and 3000 lb O-lets are good to the pressure rating of Sch 160 pipe. I forget what 6000 lb O-lets are good to. I read this in ASME B16.something or the other today (I read about 4 of them, 31.1, 16.11, 16.20, and one other today so I can't remember which one stipulated it.)

rmw
 
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rneill,
Well if a 200Lb O-let is good for the same pressure rating of Sch 80 pipe and a 3000 Lb O-let is good for a the same pressure rating as Sch 160 pipe that to me means that the O-lets are "Pressure Rated" in a sense. If they are not "pressure rated" then you would not be able to select an O-let to use!!!
 
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Specify the minimum pressure you need, let them quote to that spec. Problem solved.

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
"Being GREEN isn't easy." Kermit[frog]
 
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The primary purpose of an "Olet" is to restore the header pipe to full strength when correctly installed. Proper use of Weldolets, or for that matter any integrally reinforced branch connection fitting, all depends on what piping code you are working with. ASME B31.1 and B31.3 show MSS-SP-97 as a "listed standard". In these codes you need to specify your pipe header size/thickness and your branch size/thickness and the material spec for the fitting. Material spec for the fitting should be compatible in strength to the header pipe. If you selected the correct pipe sizes for your service, the fitting will be OK. Other codes do not accept MSS-SP-97 Annex B design method. Notably these include ASME Sec I, Sec VIII and B31.8. In these situations you must provide fitting manufacturer with applicable design conditions to allow for proper dimensioning of the fitting. For example in B31.8 service you would need to supply Design Pressure, Design Temperature, Corrosion Allowance and applicable B31.8 "Factors" (Design Factor, Temperature Factor).
 
 http://files.engineering.com/getfile.aspx?folder=3d42a6e3-4d88-42c0-a1c7-0d1e4b17a020&file=How_to_Order_Branch_Connection_Fittings.pdf
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johncates,
When you say "If you selected the correct pipe sizes for your service the fitting will be OK" this is not strictly correct. (e.g. I could select a 4"nb pipe Sched 40 which is OK for the service but if the pressure is high enough then the thickness would be no good.) I beleive you should have said " If you selected the correct pipe schedules/thicknesses for the pressure service then the fitting will be OK"
 
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big inch, star for you,
some firms don't know how to order material.
(I don't see any problem in w'lets up to 16 barg.)

Greetings
 
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some companies have more time to waste than me.

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
"Being GREEN isn't easy." Kermit[frog]
 
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A high "work rate" on fixed fee makes the most money.
Finish a job, get paid and move on to the next one.
I don't fill in the hours block, so the client just gets a /0 error there. Sometimes its big, sometimes its small, but it's always my problem, not the client's.

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
"Being GREEN isn't easy." Kermit[frog]
 
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