The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Titanium pickle tank - What plastic is economical and reliable?

Nitric-HF for titanium pickling tank. What plastic tank material will work?
Rotomolded tanks only? If it is PE - It is HDPE or XLDPE?
If it is PP - then co-polymer or homo polymer?

Any one has experience with welded HDPE tanks?

Balachander M
Aerospace - Winnipeg, MB, Canada
2003

Nitric acid removes the plasticizers from PP. If has been welded, the joint has had a fair amount removed allready. Results, joint failures in a year or two , and brittle tanks that will not take much abuse. I strongly prefer rotatationally molded PE tanks, Medium to high density, from a vendor that I trust. For a large (1,000 gal) I had a stainles steel tank with a thick vinyl liner that was replaced at about the 4 - 5 year point.

James Watts
- Navarre, Florida
2003

---

2003

Hi Balachander M

Yes, I'd agree with James Watt ... go thou to one of the rotational moulders (the larger Companies are in Ontario) and get a, presumeably, rectangular tank ... which we have in Canada up to 500 imp. gal.
l. Don't buy the 'standard' tank but ask the mfg for an increased wall thickness ... max. is 1/2" The extra cost is piddly.
2. I haven't a clue what XLDPE means. These tanks are normally made from, I believe, a medium density Pe and not from hdPe Some tanks, especially in the USA, are made from uhmwPe.
3. Go to the archives and hit # 8169 which deals more with PP and oxidizing acids.
4. Don't weld a damned thing into these tanks ... only use tank adaptors but the PVC ones, not PP. You might/might not have to change the EPDM gaskets to viton. Your choice. But you could weld stiffeners to the outside.
5. Your limiting temperature is l50 degr. F ... but one Mfg said l70 F. If, if, if you are up in the temperature range, clad the outside with fibreglass to stiffen it up BUT, BUT use a 'corrugated' cardboard inbetween. Why? Because otherwise the Pe will distort and buckle horribly whereas the corrug. cardboard will keep the FRP from tightly bonding.
6. The best material is uPVC ... but you'd get a very good life especially using a heavy wall Pe......... Question ... you say AEROSPACE ... BUT I thought that there was only Bristol Aerospace in Winnipeg?

If so and if Peter Bevan is still there, give him my regards

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

---

2003

Thank you James and Freeman Newton for the information. XLDPE is cross linked linear lowdensity polyethylene. UHMWPE- Ultra high molecular weight poly ethylene.
We are planning to keep the plastic tank in SS tank filled cold water ( to maintain the etch at room temperature).

I shall convey your regards to Peter ( if he is still around). Bala

Balachander M
- Winnipeg, Canada