On the classification and inspection of reaction vessels

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I. Reactor parameters: 1. Operating pressure inside the reactor: atmospheric pressure; operating pressure of the jacket: 0.4 Mpa； 2. Operating temperature: 120 degrees inside the reactor, 150 degrees in the jacket ； 3. Diameter: DN1300 for the reactor interior, DN1400 for the jacket ； 4. Medium: Peritoneal glue inside the tank, steam in the jacket. 5. A guide spiral plate is installed inside the jacket, with a pitch of 200 mm. II. Issues for discussion: 1. According to the 1999 code requirements, the interlayer does not meet the 150 mm diameter requirement (the maximum width of the interlayer’s cross-section is 50 mm); can it be exempted from classification? 2. According to the new safety regulations in TSG R0004-2009, both the PV and the medium meet the classification criteria; should they be classified as Category 1? But according to clause 1.4.2, is it not necessary to conduct supervision and inspection? In general, it should be designed, classified, and manufactured as a pressure vessel, but no supervision or inspection is required? 3. For devices of this size, there is a lot of illegal manufacturing; many reactors with pressure jackets are manufactured as if they were operating at atmospheric pressure. For example, for kettles of the aforementioned dimensions, the manufacturer uses an inner cylinder made of 3mm thick 304 material and a jacket made of 3mm thick Q235 material; however, the calculated thickness is much greater than this. These kettles have been in use for many years without any problems. The kettles manufactured by this factory generally have this thickness, and the company has been in operation for 10 years now, having produced over 800 units. The equipment has never had any problems. We simply can’t compete with such factories; the cost difference is too large. a. Are our regulatory standards too conservative? If not, then why have the aforementioned manufacturers never experienced any quality issues? b. Do you think more lenient regulations should be applied to similar devices? Otherwise, how can qualified manufacturers compete with others?