In-service welding of methane/hydrogen mixture pipelines
Joint Industry Project
Does welding onto an in-service pipeline that contains a mixture of methane and hydrogen results in an increased risk of hydrogen cracking?
Challenge
In-service welds can be particularly susceptible to hydrogen cracking. The primary defense against hydrogen cracking is to strictly limit the introduction of hydrogen into these welds by the proper use of low-hydrogen welding electrodes. Even though low-hydrogen electrodes are used, elevated weld hydrogen levels can result from hydrogen being present in the steel or from exposure of steel to elevated inside surface temperatures during in-service welding.
Objective
The objective of this Joint Industry Project is to determine if welding onto an in-service pipeline that contains a mixture of methane and hydrogen results in an increased risk of hydrogen cracking and, if so, to develop guidance pertaining to measures that can be taken to mitigate the increased risk.
DNV's role
- Determine the extent to which steel pipe can become charged with hydrogen when transporting methane/hydrogen mixtures
- Determine the extent to which elevated weld hydrogen levels can result from:
- Welding onto pipe pressurized with blends of hydrogen and methane
- Welding onto steel charged with hydrogen
- Develop measures to mitigate the increased risk of hydrogen cracking.
Project details
This is a multi client project and performed by international partners.
Project status
Ongoing: 2020-2022.
