Visual inspection of cylinders

Every five years, all hoses should be tested to 1 times the container pressure at 130°F (54.4°C). Also, every five years the cylinders should be inspected per DOT requirements. For containers in continuous service, a visual inspection per CCA C-6, Standard for Visual Inspection of Steel Compressed Gas Cylinders may be conducted. The cylinder does not need to be emptied and cylinder should not be stamped. 

CGA C-6.19. Standard for Visual Inspection of Steel Compressed Gas Cylinders. Compressed Gas Association, Chantilly, VA. 

This discussion may not cover all conditions, sizes, types of defects, or methods of inspection. More complete and specific coverage of the subject is found in CGA C-6, Standards for Visual Inspection of Steel Compressed Gas Cylinders, and 49 CFR 173.34 and 173.301 [10, 1]. For cylinders made from materials other than steel, see CGA C-6.1, Standards for Visual Inspection of High Pressure Aluminum Compressed Gas Cylinders , CGA C-6.2, Guidelines for Visual Inspection and Requalification of Fiber Reinforced High Pressure Cylinders , CGA C-6.3, Guidelines for Visual Inspection and Requalification of Low Pressure Aluminum Compressed Gas Cylinders , CGA C-8, Standardfor Requalification of DOT-3HT, CTC-3H, and TC-3HTM Seamless Steel Cylinders , and CGA C-13, Guidelines for Periodic Visual Inspection and Requalification of Acetylene Cylinders [W, 12, 13, 14, 15]. 

The basic elements involved in performing a visual inspection of a compressed gas cylinder include ... 

Definitions for terms commonly used for the visual inspection of compressed gas cylinders are as follows ... 

Horoscope. The horoscope enables detailed visual inspection of internal cylinder surfaces and allows for close-up inspection of affected areas through a series of lenses within a tubular assembly. 

The following sections summarize the inspection procedures provided in CGA C-6, Standards for Visual Inspection of Steel Compressed Gas Cylinders [10]. Except where noted, the focus pertains to low pressure and high pressure steel cylinders. While many of the same considerations apply to the inspection of aluminum cylinders and cylinders made of materials other than steel, the respective CGA technical publications should be consulted for specific procedures and defect limitations concerning such cylinders. See CGA C-6.1, C-6.2, andC-6.3 [11, 12, 13]. 

In the case of a marking plate (allowed only on certain cylinders) that is not sealed around the complete periphery, any evidence of corrosion between it and the wall requires removal of the plate and visual inspection of the cylinder wall. However, removal of the plate must be undertaken only by authorized repair facilities... 

As previously stated, considerations for visual inspection of steel cylinders are also applicable to aluminum cylinders. However, some differences exist with acceptance criteria. For example, aluminum cylinders must be condemned when impairment to the surface (corrosion or mechanical defect) exceeds a depth so that the remaining wall is less than three-fourths of the minimum allowable wall thickness required by the specification under which the cylinder was manufactured. 

CGA C-6.1, Standards for Visual Inspection of High Pressure Aluminum Compressed Gas Cylinders [11]... 

External visual inspection as described in CGA C-6, Standards for Visual Inspection of High Pressure Aluminum Compressed Gas Cylinders, is permitted in lieu of the periodic retest provided cylinders used exclusively for ammonia of 99.95% purity. Subsequent inspections are required at 5 year intervals [12]. ... 

Specification 3A, 3AA, and 3B cylinders used in methylamine service must be requalified by hydrostatic retest every 5 years under present regulations. Specification 4B, 4BA, and 4BW must be hydrostatically tested after expiration of the first 12-year period and each 7 or 12 years thereafter depending on the initial hydrostatic test method. Cylinders in compliance with specifications 3A, 3AA, 3B, 4B, 4BA, or 4BW that are used specifically for monomethylamine, dimethylamine, and trimethylamine service and are free from corroding components may also be qualified by an external visual inspection as described in CGA C-6, Standards for Visual Inspection of Steel Compressed Gas Cylinders [10]. Periodic hydrostatic retest is not required for specification 3E cylinders. 

C-6 Standards for Visual Inspection of Steel Compressed Gas Cylinders. A guide for establishing cylinder inspection procedures and standards to meet cylinder inspection requirements of DOT. Covers all types of steel compressed gas cylinders including those that may be visually inspected in lieu of hydrostatic retest. Current edition cited in 29 CFR and 49 CFR (16 pages). 

Employers must visually inspect compressed gas cylinders to determine that they are in safe condition under 1910.101. Visual inspections must be conducted as prescribed in the Hazardous Materials Regulations of the Department of Transportation (49 CFR Parts 171-179 and 14 CFR Part 103). Where those regulations are not applicable, visual inspections must be conducted in accordance with Compressed Gas Association, Inc. (CGA) Pamphlet C-6-1968, Standards for Visual Inspection of Compressed Gas Cylinders. ... 

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