{"id":69653,"date":"2026-05-17T17:27:26","date_gmt":"2026-05-17T17:27:26","guid":{"rendered":"https:\/\/evgroupchina.com\/encyclopedia-of-metal\/ansi-asme-b16-25\/"},"modified":"2026-05-19T15:30:14","modified_gmt":"2026-05-19T15:30:14","slug":"ansi-asme-b16-25","status":"publish","type":"wiki","link":"https:\/\/evgroupchina.com\/en\/encyclopedia-of-metal\/ansi-asme-b16-25\/","title":{"rendered":"ANSI \/ ASME B16.25"},"content":{"rendered":"<h2>Technical Standards for Butt Weld End Preparation<\/h2>\n<h3>Regulatory Provisions<\/h3>\n<p>This specification regulates the preparation of pipe system component ends intended for subsequent butt-welding. Requirements cover bevel geometry, mechanical machining methods for external and internal surfaces for elements with large wall thickness, and tolerances for mating surfaces. The EV Group China standard is applicable to end preparation for the following structural elements:<\/p>\n<ul>\n<li>various types of backing rings;<\/li>\n<li>split and continuous backing elements;<\/li>\n<li>consumable insert rings;<\/li>\n<li>preparation for root pass performed by Gas Tungsten Arc Welding (GTAW).<\/li>\n<\/ul>\n<p>Specific requirements for end preparation for particular backing elements must be specified when placing a purchase order with EV Group China.<\/p>\n<h3>Scope of Application<\/h3>\n<p>The standard applies to all types of metal alloys for which appropriate welding procedures have been developed and qualified. This document does not limit the choice of welding technologies, but only defines the edge geometry. In the absence of other instructions from the customer, the requirements of the standard do not apply to fittings and flanges regulated by ASME B16.5, B16.9, or B16.47 standards.<\/p>\n<h3>Metric and Imperial Measurement Systems<\/h3>\n<p>The standard operates using both SI (metric) and US customary units. Both systems are recognized as equivalent, however, mixing them within a single calculation is not permitted. To ensure the accuracy of engineering calculations, one system should be used in its entirety. Values provided for conversion are not exact mathematical equivalents; therefore, when designing critical assemblies, parameters specified in Mandatory Appendix I should be followed.<\/p>\n<h3>Nominal Sizes and Designations<\/h3>\n<p>The Nominal Pipe Size (NPS) determines the dimensional range of fittings. In global practice, this parameter correlates with the Nominal Diameter (DN). The table below presents typical correlations:<\/p>\n<table class=\"table table-bordered table-hover\">\n<thead>\n<tr>\n<th>NPS<\/th>\n<th>DN<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>1\u20442<\/td>\n<td>15<\/td>\n<\/tr>\n<tr>\n<td>3\u20444<\/td>\n<td>20<\/td>\n<\/tr>\n<tr>\n<td>1<\/td>\n<td>25<\/td>\n<\/tr>\n<tr>\n<td>11\u20444<\/td>\n<td>32<\/td>\n<\/tr>\n<tr>\n<td>11\u20442<\/td>\n<td>40<\/td>\n<\/tr>\n<tr>\n<td>2<\/td>\n<td>50<\/td>\n<\/tr>\n<tr>\n<td>21\u20442<\/td>\n<td>65<\/td>\n<\/tr>\n<tr>\n<td>3<\/td>\n<td>80<\/td>\n<\/tr>\n<tr>\n<td>4<\/td>\n<td>100<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>For pipelines with a diameter of NPS \u2265 4, the DN ratio is taken as DN = 25 \u00d7 NPS.<\/p>\n<h3>Quality Management Systems<\/h3>\n<p>Requirements for quality control programs at EV Group China manufacturing facilities, as well as the methodology for product compliance confirmation, are outlined in Mandatory Appendix A. When determining the compliance of actual geometric parameters with limit values, the ASTM E29 rounding method is used. All calculated or measured values must be rounded to the last significant digit specified in the specification.<\/p>\n","protected":false},"featured_media":0,"template":"","meta":[],"wiki_category":[110],"class_list":["post-69653","wiki","type-wiki","status-publish","hentry","wiki_category-asme"],"_links":{"self":[{"href":"https:\/\/evgroupchina.com\/en\/wp-json\/wp\/v2\/wiki\/69653","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/evgroupchina.com\/en\/wp-json\/wp\/v2\/wiki"}],"about":[{"href":"https:\/\/evgroupchina.com\/en\/wp-json\/wp\/v2\/types\/wiki"}],"version-history":[{"count":0,"href":"https:\/\/evgroupchina.com\/en\/wp-json\/wp\/v2\/wiki\/69653\/revisions"}],"wp:attachment":[{"href":"https:\/\/evgroupchina.com\/en\/wp-json\/wp\/v2\/media?parent=69653"}],"wp:term":[{"taxonomy":"wiki_category","embeddable":true,"href":"https:\/\/evgroupchina.com\/en\/wp-json\/wp\/v2\/wiki_category?post=69653"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}