The requirements for girth weld repairs in the Twenty-first Edition of API 1104 are much more comprehensive than those in the Twentieth Edition. The half-page section in the Twentieth Edition is now ten pages long in the Twenty-first Edition. The changes place more requirements on repair welding practices that, for a typical pipeline operating company, will necessitate the qualification of a comprehensive suite of repair welding procedures. The proposed JIP will include the development and qualification of these procedures to the requirements of the Twenty-first Edition of API 1104 on a cost sharing basis.
In a recent Advisory Bulletin pertaining to pipeline construction quality issues, repair of pipeline girth welds was identified as an area of concern by Federal Regulators in the US. API 1104 was subsequently revised for the Twenty-first Edition to provide stricter requirements and more guidance for repair welds. The revisions provide more detail in terms of what constitutes a repair (including types of repairs), what level of authorization is required for various types of repairs, how to qualify repair welding procedures, and how to qualify repair welders. While the Twenty-first Edition of API 1104 was published over a year ago, it has not yet been incorporated by reference into Federal regulations in the US. As a result, many pipeline operators have not yet adopted the more-comprehensive requirements for girth weld repairs in the Twenty-first Edition.
Repair welds are often made under more challenging conditions than production welds, which can potentially reduce the quality of completed welds. Factors that make repair welds more challenging to make include excavation geometries (produced by hand grinding), particularly for the root region of through-wall repairs, restraint provided by surrounding weld metal (higher levels of residual stress), and thermal severity (faster weld cooling rates) caused by surrounding weld metal.
Scope of work
The objective of this project is to develop industry best practice for repair of pipeline girth welds during new construction activities. The scope of this project will include the development and qualification of a comprehensive suite of repair welding procedures in accordance with Section 10 of the recently-released Twenty-first Edition of API 1104 – Welding of Pipelines and Related Facilities – that covers a wide range of applications. A guideline for selecting an appropriate procedure for a given application will also be developed. The scope will also include the development of guidance pertaining to other technical aspects of girth weld repair and repair welder qualification (e.g., preheating requirements, inspection requirements, time delay prior to inspection, minimum-required and maximum-allowable repair length, practical limits on wall thickness, etc.) that will be used to develop a generic company specification for repair of pipeline girth welds during new construction.
The primary deliverables of this project will be as follows:
- A compendium of repair welding procedures qualified in accordance with the requirements of Section 10 in the recently-released Twenty-first Edition of API 1104 that covers a wide range of applications
- A guideline that can be used to select the appropriate repair procedure for a given application
- A guidance document to address the technical aspects of girth weld repair and the practical aspects of repair welder qualification
Repair procedures for each type of repair listed in Section 10 will be qualified for each of the material groupings listed in Section 126.96.36.199 of API 1104 in addition to repair procedures for Grades API 5L X65 and X70. This effort will focus on repair of manual welds made using shielded-metal arc welding (SMAW) and cellulosic-coated electrodes. Repair procedures for mechanized gas-metal arc welds (GMAW) for materials grades from API 5L X52 through X70 will also be qualified. The following repair options will be explored:
- Repair with cellulosic-coated electrodes for specific applications with guidance on mitigating the risk of hydrogen induced cracking
- Repair with conventional low-hydrogen electrodes
- Through wall repairs using combination processes (cellulosic-coated electrodes for the root and hot passes followed by low-hydrogen electrodes for the remainder of the passes)
Depending on the number of participants in the JIP, the scope may be expanded to include additional areas of interest such as:
- Repair using low-hydrogen vertical down electrodes
- Repair using gas metal arc welding and/or flux- cored arc welding
- Repair using gas tungsten arc welding
- Repair of sleeve fillet and branch groove welds
- Repair of higher-strength materials (e.g. X80)
- Repair of welds made between line pipe and fittings (e.g. elbows, bend, flanges, etc.)
- Repair procedures for specific material property requirements including toughness and hardness
Development and qualification of repair welding procedures in accordance with Section 10 of the recently-released Twenty-first Edition of API 1104 fulfils an industry need and a JIP allows this to be done on a cost-sharing basis. The development and use of industry best practices for repair of pipeline girth welds during new construction has the potential to reduce cost and will increase safety, reliability, and quality of completed pipelines.