Questions regarding the high-pressure oxygen pipelines in the oxygen regulator
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According to the oxygen regulations, nickel and nickel-based alloys are required to be used in the area five times the diameter behind the high-pressure oxygen valve. Why is this?
Dependent on the oxygen pressure, the flammability of metals is a key factor in the use of alloys in oxygen pipelines. Depending on the chemical composition of the alloy, component thickness, temperature, oxygen pressure, and oxygen purity are the main factors that affect the flammability of metals. Depending on the flammability of the metal under operating conditions, there are restrictions on the oxygen flow rate. If the flame-retardant alloy can resist combustion at the system design pressure, there is no need for a flow rate restriction. Nickel-based alloys used in oxygen delivery pipeline systems must contain at least 50 weight% nickel, and alloys with a nickel content as high as 99+ weight% have been used in the past. However, some tables for nickel alloys list a nickel content as low as 30 weight%. Generally speaking, the higher the nickel and copper content, the greater the flame retardancy. The same is true for nickel-cobalt alloys. An example of each of certain major nickel-based alloy series is described as follows: nickel (Nickel 200), nickel-copper (Monel-400 and Monel-500), nickel-chromium (Inconel 600 and Inconel X-750), and nickel-chromium-molybdenum (Hastelloy C-276 and Inconel 625). Table of Exemptions from Pressure and Minimum Thickness Requirements. Engineering Alloys – Minimum Thickness – Exemptions from Pressure Requirements: Nickel-based alloys: C-276 – No specified value; 5.3 Mpa (750 psig). Chromium-nickel-iron alloy 600 – No specified value; 6.9 Mpa (1000 psig). Chromium-nickel-iron alloy 625 – 3.18 mm (0.125″); 8.7 Mpa (1250 psig). Chromium-nickel-iron alloy X-750 – No specified value; 6.9 Mpa (1000 psig). Monel copper-nickel alloy 400 – No specified value; 21 Mpa (3000 psig). Monel copper-nickel alloy K-500 – No specified value; 21 Mpa (3000 psig). Nickel alloy 200 – No specified value; 21 Mpa (3000 psig)
I would like to ask the original poster: what standard does the oxygen gauge you mentioned refer to? I want to know if there are any special requirements for materials or structures in an oxygen-rich environment?
GB16912 Oxygen Cryogenic Procedures – this should be it; it can be referred to for study*