A study on Activity of Titas Gas Transmission & Distribution Company ltd. (TGTDCL), Bangladesh( Part-4)

2.5.5 Operation [10].

Inspections of operational works are:

 Co-ordination of pigging programs

 Cathodic protection readings

 Foreign crossing inspections

 Daily reading as required

 Co-ordinate R. O. W. surveillance

2.5.6 Maintenance and repair [10].

 Pump and compressor preventive maintenance and repair

 Pipeline repairs

 Valve maintenance and repair

2.5.7 Inspect the pipeline integrity programs 

Pipeline integrity programs are very important part of both pipeline operation and maintenance procedures. There are several functions that are required to form a complete pipeline integrity program, such as:

 Schedule pressure testing programs

 Annual river crossing profiles

 Pipeline coating assessment programs

 Depth of cover surveys

 Internal inspection surveys [10].

2.5.8 Inspection the Preparation for Welding

Safety regulations require the welding operation be protected from weather condition that would impair the quality of the welding. Before beginning the welding, welding surface must be clean and free of any material that may be detrimental to the welding. Also, pipe sections must be properly aligned for depositing the root bead. Specifications require that carbon steel with carbon content in excess of 0.32% must be preheated for welding. In some cases; steel with lower carbon contents must also be preheated. When steels with different preheated temperatures are being welded, the higher preheat temperatures must be used to weld the seams. Preheat temperature must be monitored to ensure the proper temperature and maintain that temperature during welding.             

Qualified trained welders must be employed for welding operation. TGTDCL has it’s own welder grades specified as Titas grade-A, B, C.  For high pressure pipeline a welding procedure specification (WPS) is established and suggest to follows these procedure strictly. Welding conducted as per the welding procedure and must be tested to ensure the WPS requirements fulfilment. Welded joints are inspected visually, mechanically and by using non-destructive test (NDT) methods. Mechanical test includes tensile test, nick break test, macro tech test, etc. Test results are to be documented and record the procedure of welding operation [1-2].

2.6 Inspection and Testing

Pipeline welds must be inspected visually to ensure the performance in accordance with the welding procedure and the welds are acceptable under the appropriate specifications. In the United States, to comply with provisions of 49 Code of federal regulation (CFR), non-destructive testing is also required on welds made on a pipeline that will be operated at a pressure that results in a hoop stress of 20% or more of the specified minimum yield strength (SMYS). There are two exceptions to this non-destructive testing requirement. Non-destructive testing is not required even though hoop stress will exceed 20% of SMYS if

·         the pipeline has a nominal diameter of less than 6 in.

·         the hoop stress will be less than 40% of the SMYS and the number of welds is so small as to make such testing impractical.

Non-destructive testing must be performed according to written procedures by specially trained personnel.

Radiography (X-ray) is the most widely used method for testing pipeline welds in non-destructive method. In radiography, a picture is made on a sensitized film by exposing the film to X-ray. Defects in the weld, such as cracks, porosity, or slag inclusions, appear as spots or lines on the developed film.

A study on Activity of Titas Gas Transmission & Distribution Company ltd. (TGTDCL), Bangladesh( Part-3)

2.5 Standard Inspection Methods:

2.5.1 Material procurement inspection
2.5.2 Visual inspection
2.5.3 Design inspection
2.5.4 Construction inspection
2.5.5 Operation
2.5.6 Maintenance and repair
2.5.7 Inspect the pipeline integrity programs
2.5.8 Inspection the Preparation for welding

2.5.1 Material procurement inspection
During pipeline construction materials are inspected visually and mechanically for their physical, dimensional defects and design accuracy. Materials are pre-qualified / inspected as per international standard during procurement [1].
The most common standards are:
 American Petroleum Institute ( API )
 American National Standard Institute ( ANSI )
 American Society of Mechanical Engineers ( ASME )

2.5.2 Visual inspection
Visual inspections are important in welding jobs for construction of pipelines. Cracks, incomplete penetration, burn-through, undercut, unequal leg length, and other imperfections in the test welds shall be assessed in accordance with the applicable requirements. Undercuts adjacent to the final test weld bead on the outside of the pipe shall not exceed 1mm in depth. The test welds shall have a neat appearance. Imperfections detected by visual inspections must be into consideration and take corrective measures.

2.5.3 Design inspection
The requirements for design inspection of pipeline construction project are:
 Fluid flow capacity
 Design pressure for each segment of pipeline system

°                       External pressures and loadings

°                       Ambient influence

°                       Temperature

°                       Location of Class

 

2.5.4    Construction inspection

Inspection of pipeline construction based on:

°                       Pre-construction activities

°                       Construction activities

°                       Post-construction activities

Pre-construction activities

Inspections of pre-construction activities of pipeline are as follows:

°                     Route selection

°                     Legal surveying and land acquisition

°                     Pipe hauling

°                     Equipments and vehicles

Construction activities:

Inspection of construction activities is very important for pipeline operation and integrity. When any pipe manufacturing defects are detected during installation inspection, the defective portion of pipe shall be repaired by the applicable pipe manufacturing standard or specification or cut out as a cylinder or where necessary replaced with another pipe that meets the design requirements. Inspection shall be performed by the experienced personnel. Inspection for piping defects shall be indentified immediately prior to the application of any field coating and during lowering in and backfilling operations. Pipe and component shall be inspected for defects. Such inspection shall include but not necessarily be limited to inspection for flattening, ovality, straightness, pits slivers, cracks, gouges, dents, defective weld seams, and defective field welds. Bends shall be inspected for conformance with the free from buckling, cracks, and other evidence of mechanical damage. Where the pipe is field coated, inspection shall be carried out to determine that the cleaning/coating machine is not creating defects in the pipe. Coating shall be inspected immediately before, during and after pipe installation. Faults in the coating shall be repaired and re-inspected. Plant-applied coatings shall be inspected immediately after field-bending to confirm that the integrity of the coating has been maintained. Where applicable, each pipe shall be visually inspected prior to welding for defects in its lining. Inspection of field and shop welds is in accordance with the applicable requirements of clause 7 ^[9]. Inspection of pipe portion repaired, replaced, and altered shall be made before it is backfilled. Where necessary and as appropriate, non-destructive inspection of piping shall be performed using one or more of the following methods:

(a)        Radiographic inspection of welds in accordance with the applicable requirements of clause 7.

(b)        Ultrasonic inspection of welds in accordance with the applicable requirements of clause 7.

(c)        Ultrasonic inspection of pipe

(d)       Electrical inspection of protective coating

(e)        Inspection using internal inspection devices and

Other methods are below:

°                     Stringing pipe

°                     Welding

°                     Coating

°                     Ditching

°                     Crossing

°                     Lower-in

°                     Backfilling

°                     Compression and pump station

°                     Pressure testing

°                     Clean-up and restoration    ^[10].

Post-construction activities

After the pressure test has been completed, it is then necessary to displace the test median from the pipeline and purge the system with sweet natural gas or an inert gas such as nitrogen to make the system ready for operation.

A study on Activity of Titas Gas Transmission & Distribution Company ltd. (TGTDCL), Bangladesh( Part-2)

2.2.2 Equipment and Vehicle Inspections

All equipments and vehicles should be thoroughly inspected daily or weekly basis by the operators to monitor wear and tear. If more than one person is responsible for the equipment or vehicle operation, responsibility for inspections should be assigned to the authorise person or group.

General checks like fluid levels, belts, hoses, and electrical connection; should be checked before operating of the equipment or vehicle. This type of inspection is commonly called a walk-around or ‘pre-use’ inspection.

2.3 Checklists of Company Inspection

To ensure the company’s inspection procedures through checklists should be used. Checklists help to guide (direct) the inspector and ensure him / her nothing is missed. In addition, checklists create a detailed record of the findings from inspection and suggest corrective measures.

2.4 Government Inspections

Safety in worksites and safe work practices must comply with regulatory requirements by the state. Occupational health and safety inspectors are the authority from the government responsible for safe worksite. Government inspectors are the useful sources regarding the safety standards status about a company. The prime objective of government inspection is to meet the government safety standards, to make worksites safe and advise on safety issues on the worksite where needed..

For this reasons, government inspectors may assess record, plans, policies, equipments or work procedures. The inspectors may interview the company personnel about hazard, risks, health and safety measures.

Procedures include in inspection:

 °        Before joining, of the prepared ends of the pipe and couplings for cracks, dimensional imperfections and detrimental mating surface conditions

°          The external surfaces of the completed joint for cracks and dimensional imperfections

Inspection personnel should receive training in the following topics :

°          The principles of the joint design

°          The function of the end preparation and joining equipment

°          The inspection procedure and applicable inspection methods

°          The end preparation and joining procedure

°          Know and follow standard work procedures

°          Properly use tools and equipment

°          Know emergency response procedures

°          Properly supervise and direct workers under their supervision

  Table-2.1: Quality assurance table with inspection schedule. 
 

No.	Activity	1	2	3	Comment
1	Material test reports		x	x	Conform to                 material specification
2	Welding procedure		x	x	Examined 100% No laminations shall exceed ¼ inch
3	Welder qualification report		x		Certificate
4	Workmanship, dimensions	x			Visual
5	Material quality	x	x	x	Mill certificate
6	Radiographs/ultrasonic	x	x	x	Pressure piping welds shall be 100% X-rayed. Major structural welds shall be ultrasonically tested.
7	Hydrostatic tests	x	x	x	Test report
8	Function tests	x	x	x
9	Protective coating	x			Visual
10	Preparation for shipment	x			Visual
11	Nameplate/tagging	x			Visual

 

Legend of the table

 1          witnesses or verification

2          Checks certificates and Records

3          Contractor provides certificate and/or test document and records. 

A study on Activity of Titas Gas Transmission & Distribution Company ltd. (TGTDCL), Bangladesh( Part-1)

INTRODUCTION

  

Environmental and safety regulations become more stringent for oil and gas pipeline. Now a day in order to ensure[S1  safety in gas pipeline periodic and sudden inspections are carried out by a regulatory body within the company or outside the company.   Proper adherence to these regulations, periodic and sudden inspection are carried out to the oil and gas pipelines. In addition to [S2]  Periodic and sudden inspection, a supervisory inspection team also monitors the field level inspection works to ensure adherence to the regulations and safe operation of the gas pipeline networks.

Observing regulation, sound inspection practice also ensures adherence to the regulations and smooth operation of the system to prevent accidental damages. This will ultimately save life, money and property. In Titas Gas Transmission & Distribution Company ltd. (TGTDCL), regular inspection becomes increasingly important, as the pipeline gets older. As this time of modern age, various sophisticated technologies, developed over the years for proper inspections of pipelines are available to us. TGTDCL is the oldest and largest utility service providing organization in the country. Company is bestowed with the responsibility to transmit and market the natural gas within her franchise area. In order to distribute and market natural gas to the consumers, construction of high pressure and low pressure gas pipelines are required and their safety is a key issue to the company.

1.1 Statement of the problems

 

TGTDCL started in 28^th April 1968. Initially it started in Dhaka area. Later on  it expands it’s franchises area within  as on 30^th June, 2005 the company had a network of 9195 Km pipeline [Appendix-A] and the total number of customer was 1041732. During 2004-2005 financial years, TGTDCL sold 9118.25 MMCM gas to its customers. In view of the above statistics, it is very important to ensure that the company follows the safety and environmental regulations and ensure it by regular inspection and other preventive measures. There are many drawback in administration, technical and logistic

support, trained manpower and careless users. To overcome these problems selected objectivity and methodologies are described below. The project will study the inspection practice in TGTDCL in light of the safety and environmental regulations of Bangladesh. It will help identifying potential rooms for improvement. The study will also present a cost-benefit analysis of inspection operations.

1.2 Objectives:

°                     Study the inspection practices in TGTDCL and assess the effectiveness of the current practices.

°                     Identify rooms for improvement in the current practice.

°                     Suggest newer and / or different inspection technologies if applicable. 

1.3 Outline of the methodology:

°                     Literature review of the modern inspection technologies and methods.

°                     Literature review for the health, safety and environmental regulations of     

            Bangladesh.

°                     Collection of data and information regarding the inspection practice within the company

°                     Assess the effectiveness of the current practice.

Suggest improvement and newer / different technologies and methods.

REVIEW OF STANDARD INSPECTION METHOED

2.1 Inspection Purpose  

                  

Regular inspections mean monitor worksite conditions, and work procedures ensure company’s safety standards and regulatory requirements are being followed or not. They also enable to identify the associated hazards before these become problem. It also reveals where improvements are needed, such as: - equipment, work procedures, worker training or worksite conditions.

The end result of the inspection would be a list of potential problems and suggest corrective measures. To ensure health and safety, employees, contractors and subcontractors should follow the standard inspections procedures or methods and suggest corrective measures if necessary. All inspection findings and corrective measures should be documented and shared with others in the worksite.

2.2 Types of Company Inspections

Company inspections should be include

1.         General Site Inspections

2.         Equipment and Vehicle Inspection

2.2.1 General Site Inspections

General sites include all field and office worksites, work camps and company leisure areas such as employee lounges and cafeterias. All these sites should be regularly inspected for any possible hazards to health, including unsafe work practices and conditions.

Inspections should be scheduled according to the hazards at the sites and the work, i.e. a gas pipeline may require regular inspections.

Worksite inspections should assess the:

°                     physical layout and conditions of the site, including location, terrain, season and weather

°                     hazards of materials being handled

°                     condition of equipment and tools used

°                     work practices and behaviour of people at the site (employees, contractors, subcontractors, visitors and clients )

°                     level and quality of supervision given to workers 

Physical hazards

Physical hazard means which are present in working area and these are seen, feeling, touch by the worker i.e. site, equipment, material etc.  

Site, equipment and material hazards checklists are:-  

°                     Slipping and tripping hazards

°                     Presence of noxious gases

°                     Faulty or missing emergency equipment

°                     Improper or missing signs

°                     Faulty machinery, cables, ties downs, etc.

°                     Poor house keeping

°                     Confined spaces

°                     Inadequate or missing personal protective equipment blocked exits

°                     Overhead hazards

°                     Electrical hazards

°                     Difficult terrain for vehicular or personal movement

°                     Flammable, corrosive or explosive materials

°                     Missing material safety data sheets

Safety Inspector has the right to inspect any item/equipment either online or may order to remove for further inspection in workshop. All site personnel must co-operate with the Safety Inspector. If any serious violations of safety rules are found, safety inspector / Officer can issue a stop to work order.

 
 

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