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Lining a Pickling Tank with FRP

I am going to build a stainless steel pickling plant using HF and HNO3 as descaling agents. The tanks will be made of reinforced concrete and lined with FRP. As my product is bundle of 20-ft. length pipes, during process handling, there will be some knocking against the tank wall. What thickness of FRP is necessary to withstand this ? Some suppliers have suggested 5 mm thick. Any better solution and suggestion ?

C M Tan
steel centre - Bukit Mertajam, Penang, Malaysia
2004

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First of two simultaneous responses -- 2004

Hi C.M.

I shudder at the thought of what you are intending to do. Why? Because you'll bound, sooner or later, to scratch the fibreglass ... then you will expose the fibres ... and then dear old HF will have a good meal !

Assuming that the concrete is clean and dry, then any competent fibreglass fabricator would probably use an epoxy matte first of all, and then some structural glass, woven roving or cloth ... but of most importance will be the outer layer ... and that should be min. 1/8" (3 mm) and consist of only mat with a heavy polyester/vinylester resin content, the so-called corrosion barrier.

Knocking against the tank wall? Ah, one simple solution is to use h.d. PE, say 1/2" thick. You bolt this to the concrete top edge BUT extend it, say, 1" (25 mm) into the tank. But if your bundles are going to lengthwise impact, then I'd drape something LOOSE at the far ends. Use your imagination ... HD PE ... flex PVC ... even FRP.

There is a FAR better solution ! Before you pour your concrete, you use BEKAPLAST or something similar. This is a PVC product which comes in sheet form and has one side full of 'knobs' or 'mushroom' mini extensions so that the concrete will lock into/onto and around them and thus prevent thermal movement.

Then, when that's done, you weld up the sheet edges. Simple.

Highly acid resistant. Far better then FRP on scratch resistance, too. But you'll need a fairly competent PVC fabricator to do a good job of the final welding.

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).

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Second of two simultaneous responses --

The HF will attack the glass and your lining will be destroyed. Use PVC.

Jeffrey Holmes, CEF
Spartanburg, South Carolina
2004

I am going to build pickling tanks using 5% HF and 20% HNO3.Process temperature about 25 degree C.I propose to lined the concrete tanks using PP sheets (20 mm thick). Please give your comment. Previously my suggestion to use FRP has received strong objections because the lining would not be able to withstand abrasion and knocking during process.

C M Tan
steel centre - Bukit Mertajam, Penang, Malaysia
2005

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2005

Hi again C.M.

Well, you've changed your tune somewhat and now want to use PP. Again, please go the archives and have a look at # 8169 and maybe # 9872.

Sorry, but I can't recommend PP. By itself? Perhaps yes. But welded? NO ! Also it seems that my previous recommendation for BEKAPLAST was wrong ... I thought that it came in a PVC materials, in fact I was SURE it did .... But on checking on their website it's in PE, PP and PVDF ... and I'd only recommend PVDF.

Who, may I ask, is telling you WHAT materials to use? First it was FRP and now it's PP. Yuck.

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).

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BEKAPLAST

Out of curiosity I contacted their web site address ah, they said, ah, yes, we can supply this in PVC ... but their site doesn't say so.... so I was right after all (for a change).

THIS is the material to use. Get installation data from them, ie. how to attach to formwork before pouring the concrete

Now, coming to think of it, you never mentioned the tank sizes. Ever considered dual laminates?

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).
2005

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2005

Hi Mr. Newton,

Thank you for your interest in my problem. You suggestions and recommendations are most helpful. Just contacted BEKAPLAST supplier in Indonesia for further advice. The tanks I am building is 38" x 38" x 8 meter length. I am interested in your alternative proposal on the use of dual laminate. How to use this laminate on concrete surface. All comments are welcome.

Please excuse my ignorance. Can you define dual laminate. TQ !

Best regards,

C M Tan
steel centre - Bukit Mertajam, Penang, Malaysia

Hi C.M.

Ah, dual laminate ... sorry, but I should have explained somewhat what it is. My original definition was 'armoured thermoplastic'.

This is when you BOND a thermoplastic (such as PVC, CPVC, PVDF & some fluorocarbons) to fibreglass (FRP). The thermoplastic protects the FRP, the FRP in turn enhances the operating temperature, the impact strength (slightly) and increases the modulus and rigidity of the PVC. In other words this is a perfect synergistic marriage.... and the world's first ones were Canadian ... & I sold them.

But in view of the given length, I'd still recommend the BEKAPLAST material ... which I've used, of course ... and going by my faulty memory, the sheets come in varying thicknesses ... and I'd use a 1/4" or 3/16" thick mtl.

Don't forget to 'extend' the tank lips ... 1" upwards. Use perhaps lead inserts and just bolt the PE (sorry, Polyethylene) overhang to the top of the tank edges. Hope this helps.

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).
2005

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Because Mr.Newton is talking about KREAPLAST, I got some questions to ask Mr. Newton's comments. One of our customers is bolt&nuts producer, who pickling tank use acid proof brick and rubber lining we recommend. In the recent revamping job, they told us they want to use KREAPLAST (PP) because easy installation and cheaper.Yet as far as I know, they use 15%HCL and 100 Degree C when acid pouring into cold water. I want to know whether their choice is best?Do we have other option?

Thanks in advance

Andy Duan
fabricator - Taipei, Taiwan
2005

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2005

Hi Andy Duan,

I mentioned BEKAPLAST ... not KREAPLAST (Which is not listed on GOOGLE or other sites) which I've never heard of before anyhow.

I'd imagine that your colleague's 100 degree C temperature might well be OK for the BEKAPLAST Polypropylene ... but would check with the supplier.

Here again, there should be installation data from BEKAPLAST ... and you'd need some good welders to finish off the sheets. Be careful of people who say that they 'can' weld. Once on running tests on 1/2" thick test pieces, the union welders best strength was 30% where our trained thermoplastic welders were all hitting over 85% ... except for the lathe operator at 70% odd. As for me, I once hit 28% or was it 26%.

A dual laminate PP:FRP is OK for that temperature, going by memory ... mind you, PVDF is better but costs much more.

By the way ... and this applies to many other countries, too, your English is very good.

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).

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2005

Hi Mr. Newton,

Thanks for your correction and patience. I have checked the data sheet and found it is my mistake that there is no "Keraplast", but BEKAPLAST is the right one.

I will try to identify a qualified welder for this job.

Regarding the dual laminate, I have attended a public seminar held by German suppliers in June 2004. They claimed that they have patents on this products.If it is so, I am wondering that :

1). Is the price of dual laminate (PP:FRP) higher than that of pure PP sheet (BEKAPLAST)?

2). How about the weldability/fabrication dual laminate? Is it easier or harder than BEKAPLAST?

3). Do you think the dual laminate would gradually replace the old solution PTFE:Steel(carbon or stainless)people used for 10 years?

Sorry I got so many questions because there is not many sources available here. If you can recommend some books for more details about this, I would be very grateful.

Best Regards and May you have a good day !

Andy Duan
fabricator - Taipei, Taiwan

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2005

Andy

That claim must be l,000% WRONG ! We made the first dual laminates back in around 1962-3 ... but in later years people came out with a simpler and better bonding method.

In Canada it's called AROPOL MT93 (or MJ93 ... I forget) and is made and supplied by ASHLAND CHEMICAL and comes in, I believe, 55 gal drums .... it's a 2 component resin which is applied to the (clean and dry) PVC and after curing, ah, wonderful, one can apply a thermosetting resin to get a good bond. In the past it used to be called KRYSTEK and PALATAL A410... the latter came from Germany. I phoned them up. They have a main plant/office in the USA and say that they are currently building a plant in China.

It makes me damned incensed to hear the German claim. Yes, Germany invented PVC ... and I like to think that I held the first paper on this fabrication technique back in '74. Maybe they mean that their bonding resin is patented. So what. But not the process.

Re your questions ...

#1 ... of course a dual laminate will cost more than plain sheet materials. You have to add on labour and the costs of the bonding resin plus the cost of the fibreglass overlay.

#2 ... weldability of a dual laminate versus BEKAPLAST? Yes and No. Both materials should weld easily.

#2b ...FORMABILITY. Ah, the dual laminates BEFORE being fibreglassed, of course, would be far easier to 'form' ie, bend that BEKAPLAST because of all the 'knobs' it has. But after being fibreglassed, no, it's no longer formable.

#3 ... am unsure what you mean. If this metal combo lasts for 10 years, keep with it, don't use something else just because it might (or might not) be better or cheaper.

Sorry, I don't know of any books but there must be some around. In the 60's there was a booklet called Plastics in the Service of Man ... but those were generalities but helpful to me because I was pretty ignorant about plastics as my background was in metals (took a commercial apprenticeship in Germany in 1950 in heavy steel mfg).

If you have any more questions, shoot. I'll try to answer them ... and if you make a fortune, please buy me an XJR !

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).

I have come across company can supply & install Bekaplast lining systems here in Malaysia. I am working at a galvanising plant and part of the pretreatment process requires a series of HCl (33% concentration max.)pickling tanks and I have been constantly trying to figure out the best solution for concrete tank lining. According to some people in the field, they propose 25 mm thick CPP for lining. That is not common in Malaysia. However, I have certain faith in Bekaplast but having said that, I have yet to witness 1 here in Malaysia. I was reconsidering to go back to the old FRP solution which is safer and more economical. yes or no? I'm also thinking of maintenance and upkeep issues in the future if I go with Bekaplast? please advise! Many thanks. John

John Ng
- Shah Alam, Selangor, Malaysia
August 11, 2009

Have you resolved your issues? I am with a company that does Bekaplast lining and also have considerable FRP experience. If you are looking to maintain a temperature of 100 °C the PP material would probably not be recommended.

Robert Hauboldt
- Houston, Texas
November 20, 2009

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Dear Sir,

Option-1 Please make 40mm thick PP Tanks.
Option-2. On RCC Surface lay 3layers FRP( 450GSM) with Super vinylester resin ,above this 3-5 mm thick carbon filled screeding.

This options solve yours problem.

R.K.DOGRA

Radesh Kumar Dogra
- Delhi, India
September 9, 2011

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Over the last 15 years we went from PE, over PVC to SS (SAF 3205) They are now 8 years old and no aging is seen. We treat a lot of heavy stuff and the plastic tanks don't last.

Hans

Hans Bjerrum
- Kolding, Denmark
October 31, 2011