I always wondered if there is any difference between Rptfe (with graphite) and ptfe Cg (Carbon graphite) used for valves seats and inserts . Is it only semantic?
From a metallurgical and mechanichal point of view which are the drawbacks to making the valve seats from oxy-cut Astm 240 316 sheet metal versus making them from a forged ring or rolled bar?
Is it a problem only for the grain rolling direction transverse to the valve pressure and flow?
Is it possible in ball valves destined for Europe, to use 8.8 (EN 20898/ISO 898) bolts for the cover and trunnion? Many valve manufacturers use L7/B7 for ped valves, but I never understood why they avoid 8.8. Is it just to avoid doing the PMA for the 2014/68 EU?
Is it a problem in your opinon if i declare on valve general drawing for approval as a stem material ASTM B637 UNS N07718 (which should be similar to ams standards) and then i produce the valvole stem with an alloy 718 certififed to API 6A CRA? Isn't it better one for oil & gas aplications or...
Is in your opinion much of the s31803 duplex material (F51) sold with double certification to also cover the UNS S32205 (F60) type? Nowadays? Do a lot of steel mills produce the UNS S31803 that not also satisfies uns S32205 requirements?
Is it correct for the AISI 410 material according to ASTM A479 specification to designate it as "ASTM A479 Grade 410 (or Tp 410)" or is it better ASTM A479 UNS S41000? Today I had a debate with another technician on this topic who considered only the second designation valid.
Good morning to everybody. I am from Italy and i work in ball valves industry; i have a doubt about titanium material specifications; since Astm B381 standard talks about forgings, while the ASTM B348 talks about bars; is it possible, in your experience, to certify rolled or forged bars...
