NFPA 53-1999 Recommended Practice on Materials, Equipment, and Systems Used in Oxygen-Enriched Atmospheres

NFPA 53-1999 Recommended Practice on Materials, Equipment, and Systems Used in Oxygen-Enriched Atmospheres. 3-1* General. 3-1.1* The rate of flame propagation and ignition susceptibil- ity of materials of construction should be regarded as prime considerations in the promotion of safe design of systems asso- ciated with oxygen-enriched environments. 3-1.2 The oxygen compatibility characteristics of all materials involved in oxygen-enriched environments should be care- fully and completely evaluated under end-use conditions. Accelerated (time-temperature concentration) oxygen deteri- oration and degradation (by high-energy and ionizing radia- tion) tests for service durability also should be conducted for overall evaluation. 3-1.3 When selecting materials for oxygen service, situational or configurational flammability should be evaluated. 3-2 Nonmetals. 3-2.1* The use of nonmetals in oxygen systems should be lim- ited and their quantity and exposure to oxygen should be min- imized. 3-2.2* When selecting materials, application-specific material tests and configurations should be considered. 3-2.3* When selecting a material for oxygen systems, its ability to undergo specific cleaning procedures to remove contami- nants, particles, and combustible materials, without damage, should be considered. 4-1 Material Recommendations. Designers of equipment for oxygen use should thoroughly understand the reactivity of selected materials in oxygen-enriched environments. The designer should attempt to avoid using flammable materials; however, many materials that are flammable at operating con- ditions can safely be used in some applications by carefully avoiding ignition sources. The designer should not compro- mise safety to reduce material costs. 4-2* General Design Recommendations. Designs should con- sider system dynamics, component interactions, and operational constraints in addition to component design requirements to prevent conditions leading to fires in oxygen-enriched atmo- spheres (OEA). 4-3 Specific Component Design Guidelines. Oxygen system designers should (a)* Minimize the amount of organic, nonmetallic materials and their exposure to oxygen flow (b)*Limit gaseous oxygen pressurization rates (c)* Limit gaseous oxygen flow velocities (d)*Minimize mechanical impact (e)* Minimize frictional heating in oxygen (f)* Minimize ignition from particle impact (g)*Eliminate burrs and avoid sharp edges (h)*Minimize use-generated particles during manufacture, assembly, and operation (i)* Avoid rotating valve stems and sealing configurations that require rotation on assembly (j)* Minimize electrical arcing (k)*Avoid blind passages (l)* Avoid crevices for particle entrapment and resonant cavi- ties (Phillips) (m) Design dynamic seals to minimize particle generation and to minimize coefficients of friction and surface fin- ishes, and choose seal configurations to minimize particle generation that can cause particle impact ignitions (n)*Limit fluid-induced vibrations (over all operating...