Thrust Restraint - Buried Steel Pipe.
Thrust Restraint - Buried Steel Pipe.
(OP)
Dear all,
I want to evaluate if we have to use thrust blocks for direction changes of a welded buried pipe installation. I found a Restrained Joints design procedure herein:
http://www.dipra.org/pdf/thrustRestraint.pdf
,but for ductile iron pipes. Does anyone have used a similar procedure for steel pipes? I did not find anything in AWWA M11.
Thanks in advance.
I want to evaluate if we have to use thrust blocks for direction changes of a welded buried pipe installation. I found a Restrained Joints design procedure herein:
http://www.dipra.org/pdf/thrustRestraint.pdf
,but for ductile iron pipes. Does anyone have used a similar procedure for steel pipes? I did not find anything in AWWA M11.
Thanks in advance.





RE: Thrust Restraint - Buried Steel Pipe.
Regards
RE: Thrust Restraint - Buried Steel Pipe.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Thrust Restraint - Buried Steel Pipe.
Thanks for the reference. If I am reading it correctly, if we have let's say a large diameter buried conduit of 500 m between two anchor concrete blocks, we only have to guarantee a certain distance between fittings (where direction changes) without requiring the use of extra blocks. Do you agree?
Best regards.
RE: Thrust Restraint - Buried Steel Pipe.
Concrete thrust/reaction blocking on the other hand is traditionally employed if one is utilizing on the other hand UNRESTRAINED rubber-gasketed joining systems, e.g. simple "push-on" (with no restraint features) for steel or ductile iron pipes in pressure pipelines.
RE: Thrust Restraint - Buried Steel Pipe.
Go look at any refinery and you will masses of steel pipelines all aboveground fully welded and not a thrust block in sight. Piping operating successfully for years at 100batg or more.
"Sharing knowledge is the way to immortality"
His Holiness the Dalai Lama.
http://waterhammer.hopout.com.au/
RE: Thrust Restraint - Buried Steel Pipe.
I have worked for refineries for less than one year and I also have never used a thrust block. However this is different and I am sorry if I didn´t explained the context of my problem correctly.
I am a junior designer of pipelines for penstocks (small hydropower plants), which have relative high pressures and big diameters (more than DN700) which result in great unbalanced forces at bends that are restrained by thrust blocks in aerial pipelines. I think that for buried pipelines we won't need thrust blocks, but since this is my first time I am designing one, I just wanted to show this.
rconner,
Thanks for your comment, like I say above I just want to show that we don't need thrust blocks in buried pipelines.
Cheers
RE: Thrust Restraint - Buried Steel Pipe.
RE: Thrust Restraint - Buried Steel Pipe.
Let your acquaintances be many, but your advisors one in a thousand' ... Book of Ecclesiasticus
RE: Thrust Restraint - Buried Steel Pipe.
If the pipe is installed per AWWA standards in stable native soil then it isnt going to move. If the native soil is weak and you are worried about the pipe causing movement of the embedment then a thrust block will sink in the native soil.
"Sharing knowledge is the way to immortality"
His Holiness the Dalai Lama.
http://waterhammer.hopout.com.au/
RE: Thrust Restraint - Buried Steel Pipe.
Let your acquaintances be many, but your advisors one in a thousand' ... Book of Ecclesiasticus
RE: Thrust Restraint - Buried Steel Pipe.
I doubt if most water industry engineers ever apply Von Mises or similar in analysing a pipeline. Generally they pick a pipe from a catalogue.
I have yet to see thrust blocks on a fully welded steel pipeline in the oil & gas sector. Why is it th water industry keeps putting thrust blocks in.
"Sharing knowledge is the way to immortality"
His Holiness the Dalai Lama.
http://waterhammer.hopout.com.au/
RE: Thrust Restraint - Buried Steel Pipe.
Who knows why they continue with thrust blocks. Probably because most of their standards are derived from the non-welded joint era, but not ever having used non-welded/glued/mechanically coupled jointed pipe, I surely don't know.
Let your acquaintances be many, but your advisors one in a thousand' ... Book of Ecclesiasticus
RE: Thrust Restraint - Buried Steel Pipe.
It just never ceases to amaze me how inexperienced the foreign engineers are that post here, and yet they are doing such complex work.
I mean really. Designing 6ft diameter piping for a hydropower dam is not something to mess around with and google up the answer too. God help them all.
Real world knowledge doesn't fall out of the sky on a parachute, but rather is gained in small increments during moments of panic or curiosity.
RE: Thrust Restraint - Buried Steel Pipe.
"Sharing knowledge is the way to immortality"
His Holiness the Dalai Lama.
http://waterhammer.hopout.com.au/
RE: Thrust Restraint - Buried Steel Pipe.
Let your acquaintances be many, but your advisors one in a thousand' ... Book of Ecclesiasticus
RE: Thrust Restraint - Buried Steel Pipe.
I'm sorry for the late answer, I had other things to do, like enjoy the sun.
If you don't mind I won't comment your latest posts.
I would like to give you a Kisse – kind of stupid and [too] simplified example:
Pipe:
OD = 711 mm;
Thickness = 8,8 mm;
Bend:
Angle = 37º;
Pressure: 231 m of water;
=> Thrust force ~ 53 tons.
If we don't grab this little fellow we'll have, for a fixed beam with 16 m length:
Sigma=Mc/I= 1171 MPa = 170 ksi (I multiplied the force by cos(angle/2)).
I leave this for discussion if you're still willing to put up with me. I honestly appreciate discussing with experienced engineers.
Cheers
RE: Thrust Restraint - Buried Steel Pipe.
What standard are you working to?
Have you done you calculations for hoop and longitudinaal stress? What results did you get?
Have you considered the dynamics of the system? ie had a waterhammer analysis carried out.
Answers to these questions may determine if we are willing to help any further as we too would like to get out in the sun!
"Sharing knowledge is the way to immortality"
His Holiness the Dalai Lama.
http://waterhammer.hopout.com.au/