AWS C4.3-C4.3M:2018 pdf download.Recommended Practices for Oxyfuel Gas Heating Torch Operation
1.1 Scope. This manual describes the equipment, procedures, and safe practices for oxyfuel gas heating torch operation.It is written for the operators of torches using single or multiple heating tips and heads. It is also recommended for man-agement personnel associated with the oxyfuel gas heating torch operation and process.
Oxy fuel heating is an operation whereby various metals are heated in order to perform the following operations:
(1) Straightening and bending with mechanical force
(2) Flame straightening and cambering
(3) Stress relieving
(4) Preweld and postweld heating
(5) Fusion of coatings
(6) Flame hardening
(7) Flame shrinking
The metal is heated by the direct application of single- or multi-flames to a desired elevated temperature. The heating process may be applied to all types of metal forms or shapes. An operator can make proper compensation for the effect of the metallurgical conditions. part gecometry. and physical changes that may occur during the heating process.
In general, torch heating does not require any lengthy startup. Operations can be performed in most locations, in con-fined areas, under most conditions, and with relatively low-cost equipment. Torch heating can also be performed on completed structures without dismantling them. Although this recommended practice is not written with mandatory requirements. mandatory language. such as the use of "shall." will be found in those portions of the document where failure to follow the instructions or procedures could produce inferior. misleading. or unsafe results.
Work performed in accordance with this standard may involve the use of materials that have been deemed hazardous,and may involve operations or equipment that may cause injury or death. This standard does not purport to address all safety and health risks that may be encountered. The user of this standard should establish an appropriate safety program to address such risks as well as to meet applicable regulatory requirements. ANSI Z49.1 should be considered when developing the safety program.
Check valves or flashback arrestors may be used. However, before using these devices, the user should determine that they will allow adequate flow for the equipment being used. These devices restrict flow which could result in a backfire or sustained backfire. See Clause 8 for more information on these devices.
4.1 Oxygen Supply. Oxygen of high purity (99.5% minimum) is supplied in individual cylinders of various sizes (see Figure 1) or may be distributed by pipeline from manifold cylinders or bulk liquid tanks. Oxygen should always be called by its proper name,“OXYGEN," and should not be referred to as“AIR." Regardless of the source, sufficient pressure and flow capabilities should be available for the work to be done. Consult manufacturer's literature for pressure and volume requirements.AWS C4.3-C4.3M pdf download.