As I am sure regular readers of Valve World magazine will have seen, columnist Barrie Kirkman has been writing at some length on the topic of castings. In his monthly instalments – number nine on heat treatments will be in the November issue – Barrie has gone into a whole range of topics. And in doing so, he has highlighted just how many ways there are for errors, mistakes and imperfections to creep into the entire casting process.
Now as an industry outsider, I am somewhat surprised that this is still the case. After all, the casting process has been around for possibly six thousand years, so wouldn’t it be reasonable to expect all the problems to have been ironed out by now?
Well, apparently not, Barrie isn’t the only flow control expert who is raising this point time and time again. I recall one of my very first meetings with a refinery engineer, who when I asked about his biggest headache practically shouted “valve castings”!
And only last week, when visiting a chemical company, I heard the same message, that imperfections in cast valve bodies were a real headache.
So what’s the answer? More research? Better QA/QC? Technical training for foundry workers? Or perhaps all of the above? Now I’m not an expert, so if you have any thoughts or experiences that you’d like to share then I would really like to hear from you – as would Barrie, I quite imagine.
But let me finish on a positive note. Again, from another recent meeting, this time with a valve maker who has gradually started to source more and more castings from the Far East. To paraphrase his words, the first batch received were way below the expected standard. But by working closely with the foundry and sharing expertise on the casting process the company has been able to secure itself a reliable supply of top quality castings. However, this particular valve maker emphasizes just how important it is to continue to invest in the relationship and to be vigilant during the long-term.
So are casting defects an inevitability? Or does the old adage still hold true that “trust is good, control is better”?