Fri. Sep 24th, 2021

City gas distribution

Transporting future fuel

#20 IMS – Integrity Management system

9 min read

These regulation are meant to ensure the integrity of the CGD network by employing various techniques to address the likely cause of threat to the system and their mitigation. The IMS regulations follow the system of schedule for addressing specific issues pertaining to IMS.

These regulations shall apply to all the entities laying, building, operating or expanding city or local natural gas distribution networks.

These regulations shall cover all existing and new city gas distribution networks including sun-transmission pipelines, city gas station, distribution mains and piping facilities downstream of inlet isolation valve of city gas station including consumer meter for commercial or industrial customer and up to the final isolation valve including connecting hose to gas appliances for domestic consumer.

The objectives of IMS regulations are listed below;

  1. evaluating the risk associated with city gas distribution networks and effectively allocating resources for prevention, detection and mitigation activities.
  2. improving the safety of city gas distribution networks so as to protect the personnel, property, public and environment.
  3. bringing more streamlined and effective operations to minimize the probability of CGD network failure.

Schedule in IMS regulation:

1) Schedule 1: It covers the objective of the IMS for CGD i.e. ensuring the quality of CGD network integrity in all areas which have the potential for adverse consequences, increasing the general confidence of the public in the operation of the CGD network.

2) Schedule 2: An Integrity Management System for CGD networks provides a comprehensive and structured framework for the assessment of CGD networks condition, likely threats, risks assessment, and mitigation action to ensure safe and incident-free operation of CGD networks. Such a comprehensive integrity management system essentially comprises of the following elements

(a) Integrity Management Plan (IMP): This encompasses collection and validation of data, assessment of the spectrum of risks, risk ranking, assessment of integrity with reference to risks mitigation, updation of data and reassessment of risk;

(b) Performance evaluation of Integrity Management Plan: This is a mechanism to monitor the effectiveness of integrity management plan adopted and for further improvement;

(c) Communication Plan: This covers a structured plan to regulate information and data exchange within and amongst the internal and external environment;

(d) Management of Change: This is the process to incorporate the system changes (technical physical, procedural and organization changes) into integrity management plan to update the integrity management plan;

(e) Quality Control: This is the process to establish the requirements of quality in the execution of the processes defined in the integrity management plan.

3) Schedule 3: It include the description of CGD system – specific to the CGD for which IMS is being prepared.

Description of CGD Network should include specific description of the
primary networks, secondary and tertiary networks with respect to
design specifications, length, major installations details such as:
a) Sub Transmission Pipeline (STPL)
b) City Gas Station (CGS)
c) Odorization System
d) Steel pipeline networks
e) Secondary PE networks
f) Tertiary networks, PE, GI and/ or copper
g) District Regulating Station (DRS)
h) Isolation Valves (Steel, PE)
i) CNG station-Mother, Online, Daughter Booster Station (DBS)
j) Individual Pressure Regulating Station (IPRS), Common Pressure Regulating Station (CPRS), Metering Station (MRS)
k) Control room and/or Master Control Station (if any)
l) Instrumentation and Electrical systems
m) Supervisory Control and Data Acquisition (if any)
n) Safety Equipment
o) Customer base (PNG, CNG, Industrial, and Commercial)

Other description includes;
p) Interfaces with other Geographical Area / pipeline / Facilities
(if available);
q) Incident reporting;
r) Information on Documentation Relating to the design, construction, operations, maintenance, etc.;
s) Statutory requirements.

4) Schedule 4: This deals with the selection of appropriate IMS. The selection is made between performances based management system or prescriptive type IMS. In a country where CGD has not yet matured, the prescriptive type IMS has been preferred.

Integrity Management System for CGD Networks could employ either a Performance-based IMS or a Prescriptive type Integrity Management System. Whereas, CGD industry has gathered a reasonable good experience of CGD operations and such CGD industry is fairly mature, a Performance-based Integrity Management System is appreciated globally. However, where CGD networks are in the developing stage, a Prescriptive type of Integrity Management System is recommended. Whereas, the Performance-based Integrity Management System recognizes the experience of the entity which has been operating the CGD network but the Prescriptive type Integrity Management System is more rigorous as it considers the worst-case scenario of the failures in the CGD networks and therefore worst-case scenario for mitigation.

Though the subsequent schedule in these regulations applies to both prescriptive and performance-based types of Integrity Management System, present regulations mainly focus on prescriptive aspects in the absence of adequate historical Integrity Management System data.

5) Schedule 5: This deals with the IMS tools. The tools for integrity assessment are the primarily the ones which tell the health of the CGD system and pre determined the likely threat to the system. These are direct measurement of thickness, CP survey and pressure testing.

(a) Direct assessment and evaluation: External Corrosion Direct Assessment (ECDA) can be used for determining integrity for the external corrosion threat on CGD network segments. The External Corrosion Direct Assessment process has the following four components:
(1) Pre-assessment
(2) Inspections
(3) Examinations and evaluations
(4) Post-assessment
While implementing External Corrosion Direct Assessment and when the pipe is exposed, the company is advised to conduct examinations for threats other than that for external corrosion also (like mechanical and coating damages)

(b) Thickness assessment and periodic review against baseline values: Periodic thickness assessment for all CGD network skids and pressure vessels and comparison to baseline values shall be done once a year.

(c) Cathodic protection system surveys: Cathodic Protection adequacy survey shall be carried out so as to cover the entire steel network of pipelines so as to detect insufficient Cathodic Protection levels and other irregularities and anomalies in the steel pipeline. Suitable procedures shall be established by the operator to account for adequate Cathodic Protection levels to pipeline extensions and new projects.

(d) Pressure testing: Pressure testing is appropriate for integrity assessment when addressing certain threats, at the pre-commissioning stage itself. Pressure testing shall comply with the requirements of applicable Petroleum and Natural Gas Regulatory Board regulations.
Such other methods for integrity assessment may be also adopted by the CGD entity as it thinks fit, apart from the above-mentioned ones.

6) Schedule 6: This deals with the designing application of IMS for the CGS network. This schedule covers CGD network IMS plan which is supported by data gathering, identification of threats, consequences of threat and impact analysis and assessment of this with assigned probability. It also analyzes the performance plan, communication plan, management of change plan and the quality control plan.

7) Schedule 7: This deals with the approval of IMS. The entity prepares an IMS which is first provisionally accepted by the head of the operating team and the conformity with IMS document is certified by a TPIA. this document thereafter be accepted by PNGRB. The approval for implementation is given by CEO or director of the entity.

8) Schedule 8: It gives the implementation schedule of IMS detailing various steps and time duration.

9) Schedule 9: This deals with the review of IMS. Based on the experience of the entity the time schedule has been defined every three year for review. Further, there is a internal audit and external audit for implementation of IMS.

10) Schedule 10: This gives the detail of adequacy of manpower for different stages of project.

The entity will have to address the requirement of manpower for different stages of the project, namely: Design, construction, commissioning, operation, and maintenance. The entity which is preparing Integrity Management System should have to address the manpower requirement for its present and future operations.

Leave a Reply

Your email address will not be published. Required fields are marked *

Copyright © Citygasdistribution |All rights reserved |