Wednesday, 6 June 2012

Brewery Build #10: Fittings (revisited)

As mentioned in Brewery Build Update #4, most plumbing fittings came from the USA or China, but unfortunatly those usually take at least 2 weeks or longer for stuff to get here. Now that I have the majority of the equipment and fittings (and kegs are getting empty) I want to start brewing.  However, when I did a mock-fit-out, I was missing a small number of critical fittings and did not want to wait weeks for them to get here. So today I visited a local stainless-fittings supplier (ProChem) and as a result, was pleasantly surprised that their prices compared well to the imported fittings.  Also nice to find was that the ProChem fittings are noticeably better quality and finish than the Ebay ones - obviously they don't deliver to your door, but it's likely I'll source future fittings from them where possible.

Purchasing the local BSP fittings, also allowed me to test my earlier claim about BSP and NPT fittings being inter-changeable at 1/2 inch size.
From left: American NPT camlock, Australian BSP nipple, Chinese NPT cross, Australian BSP elbow, Chinese NPT nipple.  All these fittings fit snugly and with or without plumbing tape are tight and secure. At 1/2 inch size the only real difference between the NPT and BSP fittings is a difference in thread-pitch, so with some plumbing tape and a little care they all mate together without issue.

The other thing to mention is buying stainless washers - which are required make sure the silicon washers fit tightly and help make the tapered thread fitting bulkheads sit snugly against the side of the kegs. Washer suppliers will deal only with the internal hole-size (and the external diameter) of the washers, meaning that if you ask for "1/2 inch washers" or even explain that you want "washes to fit 1/2 inch plumbing fittings" they'll (try to) give you washers where the internal hole is 1/2 inch wide - and these wont fit onto 1/2 inch plumbing fittings (since the 1/2 inch size refers to the internal size of the fitting not the size outside the thread), as you can see below:
I think the guy at the washer-shop said the correct size was 3/4 inch but they seem to measure 13/16 inch (if that's even a real size for washer holes I don't know), the good thing is that if you go to a dedicated industrial fasteners shop, you'll pay between 5-40cents for washers that will fit 1/2 inch plumbing fittings, but that sell for $1.50-2.00 each and home-brew shops.

Before everything gets fitted, I figured it was a good idea to ensure that it was clean - especially the imported fittings. All the fittings had a bath in hot water and sodium percarbonate, then a citric acid bath and a rinse in water before drying:
The kegs will also get a wash with sodium percarbonate and - especially anywhere I have drilled, cut, filed or grinded - a good scrub (with a non metallic kitchen scrub-mat-thing) with some Stainless Steel Cleaner (which contains Oxalic acid, citric acid and other random stuff including AES, K12, ETA-2NA) which should help re-passivated the stainless, especially around the areas I have worked.
This stuff is great for cleaning up any minor surface rust (like the various external dents and scratches on the kegs), a bit of a rub with a wet kitchen-scrubby and the rust is gone and the stainless is nicely shiny and passivated again.

I mentioned earlier that the first batch of Chinese fittings were not that great quality, they'll still work fine and I'll use the fittings in non-critical areas like the sight-glass on the HLT, but still the workmanship was a bit shoddy:
The other thing to not when dealing with fittings is that they do not appear to have a standard size - the "1/2 inch size" is really a reference to the internal diameter and is essentially just a number now and not anything real.  So while they are all 1/2 inch fittings, and all mate together without much issue, the outside diameter, length and even thread-length of the fittings can vary depending on where and when they were purchased:
Each of these fittings is lined up exactly on the edge of the bench, however each is longer, taller or have longer thread-length than the other. Again it's not a major issue, however, it's something to consider if you're designing stuff that depends on specific size fittings.

Unfortunately after I washed all the fittings (as above) it seems that the external-body-bolts on the 3-piece ball-valve have rusted:
These were supposed to be all 316 grade stainless, and while the bolts are stamped 'A2' - which means they should be 304 grade stainless - they're clearly not if they've rusted after drying with a few spots of water on them. Interestingly these were purchased from two different Ebay vendors, so I'd guess that either the manufacturer or distributor has cut some corners or something. Both vendors were quick to provide refunds, and I'll pull them apart and remove the rust and be more careful, but I presume the external-body-bolts are some inferior grade of steel which will easily rust when it gets wet, so will likely need to be replaced.

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