Continue to Site

Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

Register Log in
  • Congratulations pierreick on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Weldolet - Allowable Pressure 2

Status
Not open for further replies.
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)
 
Replies continue below

Recommended for you

Sort by date Sort by votes
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]
 
Upvote 0 Downvote
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?!
 
Upvote 0 Downvote
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]
 
Upvote 0 Downvote

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.
 
Upvote 0 Downvote
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.
 
Upvote 0 Downvote
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
 
Upvote 0 Downvote
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)
 
Upvote 0 Downvote
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
 
Upvote 0 Downvote
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!!!
 
Upvote 0 Downvote
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]
 
Upvote 0 Downvote
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
Upvote 0 Downvote
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"
 
Upvote 0 Downvote
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
 
Upvote 0 Downvote
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]
 
Upvote 0 Downvote
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]
 
Upvote 0 Downvote
Status
Not open for further replies.

Similar threads

Drilling Integrity Super.
Differences in Minimum Allowable Stresses in ASME B31.3 for Low and High Pressure
Replies
3
Views
2K
GD2
GD2
jafary64
  • Locked
  • Question
Calculation for change Weldolet with pipe to pipe
Replies
6
Views
2K
LittleInch
LittleInch
Matthew L
  • Locked
  • Question
B31E allowable stresses
Replies
10
Views
419
Matthew L
Matthew L
AnisaMaski
  • Locked
  • Question
Allowable stress for flexible pipe.
Replies
2
Views
459
LittleInch
LittleInch
Drake85
  • Question
Pressure Gauge connection Type
Replies
3
Views
4K
Drake85
Drake85

Part and Inventory Search

Sponsor

Back
Top Bottom