Codes for Penstock Installation

[sgarro]

Good afternoon

We´re starting a steel penstock installation in Panama with this features:

Material: ASTM A-506 gr70
Plate thickness: 1"
Penstock Diameter: 5m
Lenght: 300m

Which codes should I follow for this installation?

Does ASME B31.1 Power piping covers this application?
Does ASME Pressure Vessel Code covers this application?

Thanks

 

[Duwe6]

B31.1 is completely wrong -- it is for steam used in power generation. B31.3 would work out well, with the added advantage that radiography/UT of welds may not be required [water at a moderate pressure]

 

[C2it]

You are starting installation.

Surely you should check which Code was used for design ??

Yes, and don't call me Shirley ! RIP Leslie Nielson.

 

[waterpipe]

As mentioned by C2it, first you should seek the design standards that are used for the penstock manufacture. Then you need different standards based on the activities such as lining, coating, welding, supports, bends, branches, anchors, etc. it is quite often that you should build your tailored specification as it's a large diameter pipe with specific issues related to the pipe wall thickness, etc. you can think of: AWWA standards especially for lining and coating, AWWA M11, ASTM A-201, A-300, A-319, A-105, A-515, A-516, A-517, ANSI/AWWA C200, etc.

Shop fabrication of pipe and fittings for this type of penstock shall conform to either "ASME Boiler and Pressure Vessel Code-Section VIII, Division 1, covering fabrication, inspection and tests or ANSI AWWA C-200 and ASTM A-139 Standards plus additional requirements.

Some additional requirements might be needed to ASME VIII for example for qualification of welders, welding procedures and radiographic inspection.

I recommend that you look for “buried steel penstocks-Steel plate engineering data,volume4” by American Iron and Steel Institute and “welded steel penstock-engineering monograph No.3” for further info.

 

[sgarro]

Thank you all!

Basically my problem is this:

In a project we are finishing right now,the penstock diameter is 4500m. We measured the roundness of the pipes, 4 measures in total to know the OUT OF ROUNDNESS, and it must comply with this:

Dmax - Dmin <= 45mm (1%) - based on ASME VIII UG-80

The problem is that some penstocks have an out-of-roundness over 1%, like 2% and 3% the most critical. I think that ASME VIII UG-80 is very rigorous, with the tolerance of 1%, for the specific case of high diameter penstock as it is for pressure vessels with much critical conditions like higher pressures and temperatures, so I was looking for a standard that may give me a little more tolerance, let's say till 3%. A lot of literature refers ASCE MOP#79 but I's been impossible for me to find it. Any ideas???

greetings

 

[waterpipe]

AWWA M11 allows out-of-roundness for steel pipes up to 5% and for steel pipes with cement mortar lining up to 3%.
Please make sure where you are making your measurements. if it's buried then the bed preparation and compaction is of great importance to control the ovality and the measurement should be made after the backfill.
for the ASCE manual, contact them through their site.

May I ask why 4 measurements and how you decide where to make the measurements along the penstock lenghts? this might give a better insight to your problem.

 

[sgarro]

Thanks!

 

[cvg]

hold on, AWWA is for water transmission and distribution lines, not for hydropower installations. You designed the penstock with a high tolerance. Why are you so anxious to accept such a critical part of the plant when it does not meet the required specs? And if you are so anxious to accept this out of tolerance pipe, why do you need to find a code that will support the new tolerance? If you did not design the penstock then get the designer to approve the change. If you did design it than just evaluate the submitted materials for constructability, leakage, pressure test etc. and either approve it or not.

 

[waterpipe]

cvg is completely right. if there are specified requirements already in place, then follow them. I also agree that penstock is a critical piece in hydropower and you should be tough on the requirements.

Regarding AWWA, steel penstock is a large diameter water transmission pipe and could be covered by AWWA. That is why AWWA is referred as the standard in many penstock design books including the references I mentioned previously. At any rate, follow the designer specified requirements whatever they are.

Achieving under 1% deflection is tough for a 4.5 m pipe unless it has really a tick wall thickness with high grade steel. Considering the normal pressures in hydro power, I think thickness calculation is dominated by penstock weight (and external loads)in your case and if buried, compaction is highly important.

 

[cvg]

you have pipes that are over 5 inches out of round. Are you sure you can even join these pipes to form your penstock? 5 meter in diameter, 1 inch thick pipe, how will your welders get these joined? At the very least, the mating surfaces at the ends need to line up and even 1% out of round will make that difficult.

 

[rconner]

This inquiry does not state specifically whether the “out of roundness” measurements contained therein are referring to individual pipes just received and uninstalled, or instead is referring to e.g. interior measurements of the pipeline at locations after installation. From one responder’s answer it appears they may have assumed the latter (or somehow knows more than stated/I do about this specific job), particularly when it was stated the job is just “starting”. If the inquiry is talking about individual pipe ends that are not yet joined/installed, I’m not sure you will necessarily find specific requirements for the out-of-roundness of such very large diameter manufactured even pipe ends in basic AWWA or even ASCE documents. There are perhaps many reasons for this, including that large pipes of all materials from a practical standpoint are simply not perfectly round, or due to their flexibility and size may might even sag considerably under their own weight, let alone service loadings (unless e.g. ring girders and/or temporary internal bracing is applied). Another reason, is that even some carefully rounded and applied temporary bracing or stulls can understandably be dislodged or even are deliberately/understandably removed for various reasons at points in the process, and this doesn’t in and of itself mean that is bad pipe, nor that there is even anything at all really ob(re)jectionable about that pipe (it may mean however that someone might again have to re-round the end or pipe in assembly/fitting operations, that I believe at least some installers are experienced in and capable of doing for good connections).

That being said, and perhaps contrary to the inference of another response, I don’t believe that AWWA M11 really says out-of-roundness of steel water pipes of 3-5% is allowed. At least at one point, what this manual in fact said was, “When required, the design, installation, and performance of pipe bracing during transportation and installation is generally the responsibility of the contractor.” While I am not going to hold myself out as any sort of expert in matters involving five meter diameter pipes, this phraseology may be due to the quite job-specific complexity of bracing etc., i.e. exactly what e.g. is expected of or by internal bracing, including what it is intended to accomplish upfront and/or in some cases even while/after pipes are buried in the specific applications. This statement may also reflect that there could be different abilities of contractors, in different areas and with different fitting-up equipment and expertise etc., to practically deal with whatever pipe shapes or bracing is involved in the specific application (maybe kind of alluded to by Mr.cvg). As to ultimately what is acceptable, I guess the desired shape should be available and affordable (to build the project in the time frame when it is needed, and with available money), and it can certainly be argued ultimately would be most helpful if it will also work!
Everyone have a good weekend.

 

[waterpipe]

As said before, one should specify where the deflection of pipe is being measured. In my previous responds, I've assumed that the measurements and deflection control are after the installation.

Regarding what AWWA M11 really says, please take a look to the manual under "6.2.deflection determination":

 

[Oscarvs]

sgarro... Do you sure that material spec is ASTM A506 Gr 70?... I think that ASTM A516 Gr 70 is correct specification, also I suggest you will be indicate us the final service for this steel penstock.
Some applications include the water conduction for hydropower generation (fall water), if it is your case, the pressure difference (by level difference or high) is the main risk. You could be install the penstock sections with problems on the top of system (low pressure zone). I coincide with CVG about the difficulty for assembly the sections with problems, because to penstock thickness added to the site difficulties.