ASTM International

Standard Guide for Nondestructive Testing of Thin-Walled Metallic Liners in Filament-Wound Pressure Vessels Used in Aerospace Applications
 N E2982

Annotation

This guide discusses current and potential nondestructive testing (NDT) procedures for finding indications of discontinuities in thin-walled metallic liners in filament-wound pressure vessels, also known as composite overwrapped pressure vessels (COPVs). In general, these vessels have metallic liner thicknesses less than 2.3 mm (0.090 in.), and fiber loadings in the composite overwrap greater than 60 percent by weight. In COPVs, the composite overwrap thickness will be of the order of 2.0 mm (0.080 in.) for smaller vessels, and up to 20 mm (0.80 in.) for larger ones.

This guide focuses on COPVs with nonload sharing metallic liners used at ambient temperature, which most closely represents a Compressed Gas Association (CGA) Type III metal-lined COPV. However, it also has relevance to (1) monolithic metallic pressure vessels (PVs) (CGA Type I), and (2) metal-lined hoop-wrapped COPVs (CGA Type II).

The vessels covered by this guide are used in aerospace applications; therefore, the examination requirements for discontinuities and inspection points will in general be different and more stringent than for vessels used in non-aerospace applications.

This guide applies to (1) low pressure COPVs and PVs used for storing aerospace media at maximum allowable working pressures (MAWPs) up to 3.5 MPa (500 psia) and volumes up to 2 m3 (70 ft3), and (2) high pressure COPVs used for storing compressed gases at MAWPs up to 70 MPa (10,000 psia) and volumes down to 8000 cm3 (500 in.3). Internal vacuum storage or exposure is not considered appropriate for any vessel size.

The metallic liners under consideration include but are not limited to ones made from aluminum alloys, titanium alloys, nickel-based alloys, and stainless steels. In the case of COPVs, the composites through which the NDT interrogation must be made after overwrapping include, but are not limited to, various polymer matrix resins (for example, epoxies, cyanate esters, polyurethanes, phenolic resins, polyimides (including bismaleimides), polyamides) with continuous fiber reinforcement (for example, carbon, aramid, glass, or poly- (phenylenebenzobisoxazole) (PBO)).