Issues with water used for product pressure testing
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The main materials used for the heat exchangers produced by our company are brass and HT200 castings. Groundwater was used for pressure testing the product, and it started to rust just 40 minutes after it was finished. I’ll ask the experts in the future what kind of water is used for pressure testing. I heard that adding a chemical reagent to the testing process might solve the problem ?
Are there no requirements regarding water quality specified on the drawings? I’ve never worked with copper ones, but for stainless steel ones, the drawings usually specify that: ‘The chloride content in the water used for the hydrostatic test must not exceed 25 mg/l. After the hydrostatic test is successful, any water residues must be removed and the surface dried.’ ”Similar requirements should probably apply to copper equipment as well; I haven’t encountered such cases, so this is just my personal opinion. For reference only
There are no drawings available~ Now the customer requires that there should be no rust inside the casing either. It’s coated with anti-rust paint, but it seems that it won’t work in the long run :(
You produce oil-water heat exchangers, right? The key point is to completely drain any water remaining after the hydrostatic test, and dry it out using dry compressed air; if conditions permit, hot air can be used for cleaning. Our company uses this method nowadays.
Our unit is also worried about the water remaining inside the cylinder shell after pressure testing. I’ve heard that Zhejiang University is researching the addition of reagents to water; after testing the products in such water, the products fail to remain attached to the surface of the water. I’m quite looking forward to it. For some products as well, a layer of clear film on the product’s surface can help prevent water from remaining there.