Cylinders visual inspection

Guidelinesfor Periodic Visual Inspection and Kequalification oJA.cetylene Cylinders, Pamphlet C-13, Compressed Gas Association, Arlington, Va., 1992 A.cetylene, Pamphlet G-1, Compressed Gas Association, Arlington, Va., 1990. 

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. 

No chlorine gas 2a. Chlorine cylinders 2a. Visual inspection. 2a. Connect cylinders or replace empty... 

Emulsions are prepared using various ratios of the two surfactants. The total surfactant concentration is kept constant (e.g., 10%) based on the oil phase typically, for a 50 50 emulsion, 5% surfactant is used. The emulsions are placed in cylinders and their stability is assessed by visual inspection (looking for any oil separation), by droplet size analysis (e.g., using a Malvern Master Sizer), and by measuring the interfacial tension. For an 0/W emulsion the stability, droplet size and interfacial tension are plotted as a function of the % surfactant with a high HLB number. The stability reaches a maximum at an optimum % of the surfactant with the high H LB number, and at this optimum ratio the droplet size and interfacial tension reach a minimum. For W/O emulsions, the stability droplet size and interfacial tension are plotted versus % surfactant with a low FI LB number. The stability reaches a maximum at an optimum % of the surfactant with the low H LB number, and at this optimum ratio the droplet size and interfacial tension reach a minimum. 

New cylinders and cylinders returned to use after any pressure test should be subject to an internal visual inspection. 

This section examines inspection requirements and can provide general guidance to cylinder owners, fillers, shippers, and users concerning the considerations involved in setting up standard operating procedures for visual inspection. 

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 Hazardous Materials Regulations of DOT and similar regulations of TC require that cylinders be periodically requalified including a visual inspection to determine their suitability for ongoing service. A formal visual inspection is authorized instead of the periodic hydrostatic retest for certain low pressure cylinders dedicated for noncorrosive gas service. Specific details for this allowance can be found in DOT regulations under 49 CFR 173.34, or CAN/CSA B339 and B340 [1, 3, 4]. Otherwise, visual inspection is a mandatory supplement to a hydrostatic test. 

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. 

Three categories of cylinders required to be visually inspected are ... 

The first category covers cylinders exempted from hydrostatic retesting requirements of DOT and TC by virtue of their exclusive use in non-corrosive gas service. Since they are not subject to internal corrosion they do not require internal shell inspection, and, therefore, can be requali-fied by an external visual inspection. However, if internal corrosion is suspected, cylinders of this type should be internally inspected and hydrostatically tested. 

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]. 

High pressure steel cylinders. The following general rules should be applied during visual inspection ... 

Permanent attachments on cylinders may lose their intended function through service abuse. These attachments and the associated portion of the cylinder must be visually inspected. 

Permanent attachments such as footrings, headrings, neckrings or marking plates should be inspected to make sure they are in place and firmly attached. The area of attachment to the cylinder should be checked for possible entry of moisture to the cylinder surfaces that cannot be seen. In the case of adhesive attachments, any evidence of a break in the seal is cause for removal of the attachment. The use of a dull probing tool is recommended. Attachments made of plastic also must be checked carefully for gouges or splits, which would require their removal. When the cylinder bears a removable attachment such as a removable boot (footring), the attachment must be removed for visual inspection. 

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. 

Interior corrosion is best evaluated by a hydrostatic test combined with careful visual inspection. Ultrasonic thickness-measuring and flaw-detection devices may be used to evaluate specific conditions. Corrosion limits for both low and high pressure steel cylinders were dis-... 

A cylinder must be rejected and held for further evaluation when doubt exists from a visual inspection as to its suitability for continued service. Where the bottom of the defect cannot be seen or where the extent of the defect cannot be measured by various inspection instruments, the cylinder must be condemned. Such internal defects are fabrication irregularities. 

An external visual inspection must be performed to ensure the cylinder is free of arc bums, evidence of exposure to fire or excessive heat cuts digs gouges dents corrosion pit-... 

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

CGA C-6.2, Guidelines for Visual Inspections and Requalification of Fiber Reinforced High Pressure Cylinders [ 12]... 

CGA C-13, Guidelines for Periodic Visual Inspection and Requalification of Acetylene Cylinders [15]... 

CGA C-6.3, Guidelines for Visual Inspection and Requalification of Low Pressure Aluminum Compressed Gas Cylinders, ed., Compressed Gas Association, Inc., 1725 Jefferson Davis Highway, Arlington, VA 22202. 

Only cylinders that meet TC/DOT specifications 8 or 8AL or 8WC, and also meet requirements for fillings of a porous material and a suitable solvent, can be used for acetylene service. DOT/TC regulations prohibit shipment of cylinders containing acetylene gas unless they were charged by or with the consent of the owner. A periodic requalification of acetylene cylinders is required by DOT and is described in CGA C-13, Guidelines for Periodic Visual Inspection and Requalification of Acetylene Cylinders [14]. 

Cylinders made in compliance with TC/DOT specifications 4, 3A, 3AA, 3A480X, 4A, or 4AA480 used exclusively for ammonia of at least 99.95 percent purity may, in lieu of hydrostatic retest, be given a complete external visual inspection at the time such periodic retest becomes due. See 49 CFR 173.34 (e)(13), (e)(14) [9]. 

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