Work Package 4: Integrity

Leader: DBI GUT

Partners

TNO, CMI, GDF, GE PII, IGDAS, Gasunie, ISQ, MRC, Statoil and Total

Scope and Objectives

The aim of integrity management (IM) can be defined as providing:

“…the information for an operator to effectively allocate resources for appropriate prevention, detection, and mitigation activities that will result in improved safety and a reduction in the number of incidents.”

“….a process that an operator of a pipeline system can use to assess and mitigate risks in order to reduce both the likelihood and consequences of incidents.”
(Source: ASME B31.8s)

To run a proper integrity management is essential for the safe and effective operation of a pipeline system. The currently applied integrity management for natural gas pipelines fulfil these obligations.
In order to prepare the existing natural gas grid for the transportation of hydrogen rich gasses it’s important to ensure that a suitable integrity management is available beginning from the first day of the hydrogen transportation. The development of an IM considering the effect of hydrogen is necessary as this promising energy carrier can have an unwanted and perceptible influence on the material properties of steel.

The aim of the WP4 (Integrity) in the Naturalhy project is to provide a specification for an integrity management tool (IMT). The specification to be developed will meet the needs raised by the challenge to transport hydrogen in the existing pipelines, which were constructed to carry natural gas. Furthermore the effect of introducing hydrogen on the costs for operating the integrity management will be investigated.
It was decided to develop a specification instead of a compiled software tool as a specification provides the flexibility to be used by pipeline operators across Europe independent of the software environment of the single companies.

In order to succeed with the development of a proper IM specification and the determination of the effect on the costs, as described above, the following subtasks have to be done:

Subtasks and Progress

Task 4.1 Description of degradation mechanisms and realistic defects

Aim: to establish an appropriate description of defects on transmission pipelines

This task has been fully completed so that a generally supported view on the most realistic threats for pipelines has been established. Four reports have been prepared as final versions:

• Steels for gas transmission pipelines

• Knowledge of realistic defects

• Hydrogen Induced Corrosion

• Typology of Corrosion Defects

Task 4.2 Defect criticality

Aim: To determine critical defect sizes in pipelines transporting hydrogen gas.

The results of a first sensitivity analysis have been reported. A first software model for the prediction of the probability of failure (POF) in natural gas and hydrogen (and mixtures) has been set up. Based on the input data (defect geometry, loads, material properties, maintenance, probability of detection etc.) the model is able to determine the POF for a single defect or of a complete pipeline.

Task 4.3 Performance current inspection tools and identification of needs for improvements

Aim: The performance of the current inspection tools has been identified within this task.

The results of the investigations can be found in the following reports:

• In-line inspection technologies

• Non-intrusive inspection tools for unpiggable pipelines and

• Investigation of guidelines dedicated to gas transport pipeline inspection

Task 4.4 Improvements inspection and monitoring tools
 

Aim: identification of candidate improvements in NDE technologies

Part on NDE techniques
It is planned to perform experimental tests to identify the detection capability of cracks in girth welds using a MFL pig. An arrangement how to test the MFL tool have been developed. The tests are planned for 2007.

Part on Cathodic Protection
The general aim is to develop a prototype system for remote monitoring of pipelines connected to a control centre in which a real time display of the protection levels is provided by linking the monitoring system to the computer models. This task is ongoing.
 

Task 4.5: Repair methods
 

Aim: Investigation of the suitability of currently used repair methods for the hydrogen service and determination of the maximum allowable defect size to be repaired.

The task is ongoing and a draft version of the report “Sensitivity analysis of Clock Spring repair to Hydrogen gas – Effect on burst pressure” has been completed.
Furthermore numerical calculations regarding the suitability of metallic sleeves, to repair steel pipelines, are underway. Beyond this the first investigations of the repair technology “weld deposit” and their suitability for hydrogen charged steels has been carried out.
 

Task 4.6: Resource allocation
 

Aim: to establish a functional specification for a cost optimisation tool

A general flow chart describing the maintenance activities has been set up. Furthermore the hydrogen effected parts where identified. The task is ongoing.
 

Task 4.7: Integrity Management Tool
 

Aim: to establish a functional specification for an Integrity management Tool that enables taking account of hydrogen addition

The report “Principles of Integrity Management” is currently underway and a draft version will be available by the end of May 2007. The task is ongoing.