The purpose of this amendment is to improve the quality of welding performed on gas and liquid pipeline facilities under Parts 192 and 195, respectively. In Part 192, the amendment incorporates by reference sections 2.0, 3.0. and 6.0 of the 1973 (13th) edition of API Standard 1104, "Standard for Welding Pipe Lines and Related Facilities." Sections 3.0 and 6.0 of the- 13th edition are incorporated by reference in Part 195. However as discussed hereinafter, the standards in subsection 6.9 for depth of undercutting adjacent to the root bead governing acceptability of a weld are not adopted the amendment also makes certain editorial modifications in the regulations for clarity. Other changes make the transition from the currently referenced llth edition to the 13th edition less burdensome for operators and carriers.