ASME B16.9 Piping Components: An Analysis of the Critical Dimensions

EasyChair Preprint 5022

Abstract

Pipe components such as elbow, tees, and weldolets are produced at various places in the world (China, Italy and USA). Although the component is produced in accordance with standard ASME (American Society of Mechanical Engineers) B16.9, measurements show variation in geometry. In piping component design, the geometries are assumed as perfect in accordance with producer’s specification. Unfortunately, ASME B16.9 specification is limited on the details and allows for deviations within a product. For example, a long radius bend has outer diameter and bend radius. Often a specification does not include more than the minimum standards which allows for significant wiggle room for the fabrication process. This requires a conservative approach in design that results in incorrect dimensioning of the components. This leads to extreme scenarios from unnecessary use of materials and waste of limited resources to weak fittings that can break before the expected lifetime is reached. Hydrogen Induced Stress Cracking (HISC) is a major concern when piping components made of duplex and super-duplex are used for subsea installations. HISC occurs due to hydrogen diffusion into the piping which may under high stress causes the pipe component to crack. The focus of this article is based on the standard ASME B16.9 long radius elbows. The pipe size and schedule range is NPS 2-8 and SCH 80-120-160, made of duplex and super duplex materials. A series of measurements were taken utilizing an ultrasonic thickness gage. Measurements were taken at critical locations of the elbow at 5 cross sections including the intrados and extrados. From the results of the measurements, the critical characteristics and dimensions are identified. The results are also compared with the nominal straight pipe dimensions in ASME.

Keyphrases: ASMEB16.9, FEM, Pipe Elbows, Standard Components, Ultrasonic Thickness Gage, pipe bends, piping

@booklet{EasyChair:5022,
  author    = {Gwen Anderson and Ida Helene Gjerde and Sondre Luca Helgsen and Mladen Jemenica and Rajan Kumar Thapa},
  title     = {ASME B16.9 Piping Components: An Analysis of the Critical Dimensions},
  howpublished = {EasyChair Preprint 5022},
  year      = {EasyChair, 2021}}