scope:

This publication gives guidance on the mechanical integrity of acetylene generator systems using calcium carbide added to water, known as wet generation. This guideline is limited to vessels and systems with a maximum operating pressure of 15 psi (1 bar).

This publication includes the following elements of an MI program:

• identification of equipment and systems that are part of an MI program including criteria of selection based on credible failure mechanism and consequence;

• minimum maintenance recommendations for the MI covered equipment and systems;

• minimum inspection and testing recommendations for the MI covered equipment and systems; and

• industry acceptable inspection/testing deficiencies of MI covered equipment and systems.

This publication identifies potential failure scenarios for acetylene generator components. The failure scenario shall be a credible one that does not depend on multiple abnormal conditions taking place at one time. The scenario also does not depend on the failure of a safety protection device such as a pressure relief device.

The publication identifies the consequences of each failure scenario:

• If the component failure leads to an uncontrolled release of a hazardous material, the consequence of the failure is considered a loss of containment. In this publication, the main hazardous material is acetylene. Calcium carbide release is potentially hazardous as, if exposed to water, it will create acetylene carbide lime (also known as calcium hydroxide or lime slurry) is potentially hazardous because the lime water is normally saturated with acetylene and can release acetylene if the temperature rises. Loss of containment can lead to a fire, explosion, environmental impact, or personnel hazard. In this case, the consequence of the component failure is considered a mechanical integrity event. For these consequences, this publication lists the following recommended practices: inspection method, minimum recommended frequency of inspection, and the acceptance criteria for the inspection;

• If the component failure leads to a controlled release of a hazardous material (for example, the discharge of a pressure relief device to a safe location), the consequence of the component failure is considered an operational issue only and is not covered by this publication; and

• Minor leaks on the low pressure part of an acetylene plant are considered to be an operational issue, not MI.

Auxiliary systems are excluded from this publication if their failures do not lead to an uncontrolled release of a hazardous material.

For details on the operation of acetylene generators, see CGA G-1.10, Guideline for the Safe Operation of Acetylene Generators [1].¹

¹ References are shown by bracketed numbers and are listed in order of appearance in the reference section.