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GRP Adhesive bonded Joints - water

GRP Adhesive bonded Joints - water

GRP Adhesive bonded Joints - water

(OP)
Buried pipework within a water storage and pumping station facilities is specified to be GRP (glass reinforced plastic). Diameters 300mm to 1200mm. Rather than using standard spigot and socket (bell) joints with thrust blocks the designer has adopted to use tapered adhesive bonded spigot and socket joints:  My concerns are

1) Time to make joints
2) Reliability - if pipe fails hydrostatic pressure test then it will be a major task to make repair ?  
3) Quality control (we are in Africa)
4) Costs
5) Lack of flexibility

I have no experience of making adhesive bonded joints on large diameter GRP pipelines. (Pressure rating 16 bar) I would welcome any comments particualrly on costs compared to push in spigot and socket with thrust blocks and time to make joints.

Total length considering all facilities is over 20km.  

RE: GRP Adhesive bonded Joints - water

It will all be down to what you have in the specifications. Hopefully, ISO 14692 is being used to give you some chance of leverage on the quality aspects.  The design should have been undertaken by a reputable GRP design house, under a subcontract from the GRP manufacturer, then the selection of joint should have had a very sound basis.  Your chances of maximising quality have been diminished by a) using a tapered joint and b) using an adhesive joint above DN 500 in a tropical climate.

Hopefully, before it gets to the hydrotest stage, you will have put all the fitters, supervisors, and inspectors through the training and qualification programme detailed in ISO 14692-4; that way you will get a heads up on the feasibility and quality issues you will face when it comes to the actual pipe installation.  During pipe installation, as well as having the manufacturer on site to supervise, it is advisable to perform hydrotest on 500 m sections as construction progresses in order to catch poor quality early.  When consistency has been achieved you could agree to allowing longer intervals between hydrotests.  I wish you much luck.

Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdoweb/

RE: GRP Adhesive bonded Joints - water

(OP)
Steve - thanks for your response - This is a water conveyance project The base specification is AWWA C 950 and design manual AWWA M 45. ISO 14692 is not specified -.

The contract is design and build. The contractor is not in control of his design consultant and the designer is producing inappropriate solutions, such as this one.  The site labour is not highly skilled and I already have concerns of maintaining quality with GRP pipes using push in bell and spigot joints. There is little prospect of achieving quality using adhesive bonded tapered joints! We cannot prevent the contractor from adopting expensive inappropriate solutions. I need to make him aware of the quality problems, additional cost and potential programme delays. I have no experience of using GRP adhesive bonded joints and I cannot quantify these in comparison to push fit spigot and socket joints. Any advice is welcome.

Brian

RE: GRP Adhesive bonded Joints - water

My only recommendation will be to alert the GRP manufacturer ASAP.  If they have any semblance of knowledge about the effects of bad publicity on future sales then I'm sure that they will wish to mobilise in order to prevent an abject, and avoidable, disaster from occurring with their products.  If that is not feasible then it looks like being a wing and a prayer job.

Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdoweb/

RE: GRP Adhesive bonded Joints - water

BRIS, you may be interested in the thread at http://www.haestad.com/hmicom/listserv/archive/default.asp?action=thread&;messid=24558&v=n&searchid=96968.  The 2004 Romer et al ASCE paper mentioned by Mr. Axworthy at the end of this thread may be of particular interest to you, in that I understand it was written by a large consultant engineering firm that was given some charge, perhaps not much unlike yours for a fiberglass water project (then “purportedly the largest application of fiberglass pipe in the world”).  What may be of some further value to you (and maybe even worth spending a few coins to ASCE Publications) is I think those authors saw fit to publish this voluminous paper after the project was finally completed, and in the paper the authors provide a good bit of experience and perhaps some helpful guidance for many matters that are apparently not now contained in the standard to which you refer.  I have heard also that some form of fiberglass pipe was reportedly used beginning a few years ago on a very large water project apparently south of you in Botswana etc. (that for whatever reasons apparently suffered some quite severe time and cost overruns) – you might check with some folks having verifiable experience in this regard.  
I will otherwise only say that it is obvious that the basic pipe barrel material is not homogeneous/nor equally strong in all directions like some other pipes (it is instead obviously reliant on the actual amount and orientation of reinforcements within the wall, and of course on who designs this), and this can cause field inspection and uncertainty issues when actual loadings/deformation/settlements/movements etc. might not be predictable in all areas of a pipeline project.  In other words it is much more difficult for the basic strength of a particular pipe etc., damaged or undamaged, to be independently verified in the field (e.g. by putting a caliper to the wall thickness etc.)!      

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