Oil, gas and Abington - the first half century

TWI Bulletin, March - April 1996

Stuart Bond joined TWI from industry in 1992 as a Research Corrosion Engineer for materials. He has since changed his responsibilities within TWI to Industrial Membership development for the oil, gas and petrochemical industry and power generation sectors.

A long-standing successful partnership has been built up by TWI with oil, gas, petrochemical and chemical industries. Stuart Bond reviews TWI's considerable involvement over the past 50 years.

Work undertaken covers both upstream and downstream operations, and encompasses the entire range of organisations in this sector - such as operators, design and fabricating engineers and materials and equipment suppliers. Since the formation of TWI, the oil, gas, petrochemical and chemical sector has held a significant share of TWI's Industrial Membership. The following companies, or their forbears, are listed in TWI's first annual report (1946):

Babcock Energy
BHP
John Brown Engineers & Constructors
ICI
Lloyd's Register of Shipping
Monsanto
Shell
Whessoe

With a few exceptions, all the major global operators, many suppliers of equipment and services to this sector and the certifying and licensing authorities are currently Industrial Members of TWI (see Table 1).

Table 1: Current Industrial Member companies in the oil, gas, petrochemical and chemical industry sector

Today the sector represents one of the most significant sources of income and activity at TWI, see Fig.1. Developments and problems faced by the industry are constantly being addressed by staff at Abington, as an extension to companies own in-house resources. TWI strives to ensure that its programme of fundamental research (the Core Research Programme) and involvement in international standards committees accurately reflect the needs of the sector.

The oil, gas and petrochemical team and panel

The Team, whose chairman is currently Reza Razmjoo, aims to highlight new areas of material use and methods of joining, inspection and assessment of suitability for use. This ensures that proposed projects should take into account the needs of this sector. Working relationships between contacts in member companies and TWI staff help to ensure a rapid transfer of knowledge as new technologies are being developed, which allows a quick uptake in industrial use. The focal point for the Team is TWI's Structural Integrity Department.

The Industry Panel comprises Industrial Member representatives from the sector. It meets regularly as an open forum to discuss issues of new technology, materials performance and reliability with TWI specialists and invited speakers. Its aim is to ensure that the relevant activities of TWI are directed to the benefit of the oil, gas and petrochemical industries in terms of consultancy, research, technology transfer and training and certification.

Typical activities covered by TWI in this sector

• Structural integrity and reliability
• Non-destructive testing
• Materials
• Corrosion
• Repair
• Life extension
• Pipeline integrity
• High temperature properties
• Surfacing
• All aspects of joining technology
  

From research and consultancy to training and technology transfer

A unique combination of staff expertise is available to extend Industrial Members' in-house resources to tackle problems from design, materials selection, joining process and procedure development, specialist in-service NDT and on-site metallography, failure analysis, repair and remedial actions, through remaining life assessment to decommissioning, Fig.2.

A new initiative for 1996 is the Asset Inspection and Maintenance Strategy (AIMS) activity. It involves all of TWI's activities in support of the integrated plan for maintaining plant at optimum operational status without excessive interruption for unnecessary 'planned' inspection, and without incurring downtime due to failures resulting from insufficient assessment of the plant.

Similarly, TWI continues to research into the performance and joining of materials such as plastics and composites, surfacing with ceramics and corrosion resistant alloys. This gives industry increased confidence in their safe operation, inspection and service life characteristics so they can successfully use these materials in new applications.

TWI's training activities provide industry specific courses (Table 2) and courses tailored to a company's needs. A recent example of this is a two-year contract to train inspection personnel for Shell Petroleum Development in Nigeria.

A comprehensive selection of examinations giving qualification to ASNT, BGAS, CSWIP, EWF and PCN plus underwater inspection are also provided by TWI.

Working with industry

Examples of research and consultancy carried out by TWI to assist the oil, gas and petrochemical sector include: development of new materials such as plastics and reinforced composites for weight-saving and corrosion resistance, and ceramics for wear resistance.

Wet underwater welding

Wet underwater welding has been studied by TWI since the early 1970s. In 1995 work was carried out in the new diving tank facility (6.5m deep by 8m dia.) at the Underwater Operations Centre of TWI North, Fig.3, to evaluate the performance of commercial wet underwater MMA electrodes at 6m depth on 8mm thick plate. The project simulated typical repair requirements for offshore structures, ship repair and harbour/jetty sheet pile work. This work remains confidential to the sponsor(s). Access to GSP data is available to companies who pay the appropriate full participation fee.

Table 2: Forthcoming training courses with specific relevance to the oil, gas and petrochemical sector

Study of thickness effect in fatigue of welded structures

The history of TWI and fatigue of offshore structures is well known. TWI has been working closely with the North Sea developments since the mid-1960s and had considerable impact with the UK Offshore Research Programme (UKOSRP), to develop the codes for offshore structures and the study of corrosion fatigue. More recently fatigue tests on large-scale tubular nodes have been performed to examine the validity of the thickness effect in fatigue of welded structures. Initial indications from testing of 75mm thick 1.5m diameter tubulars show that the existing thickness penalty is over-conservative and therefore governing codes of practice may possibly be relaxed, giving significant cost and weight savings.

Tension leg platforms and FPSOs

The offshore-industry is working fields at ever-increasing water depth, and has developed plant and production technology to meet the severe challenges that these finds present. TWI has assisted Conoco in establishing the material and weld quality of tethers anchoring the Heidrun floating concrete platform to the seabed. Each tether was designed to withstand loads up to 2000 tonne, and to remain in operation without repair for the entire platform life of 50 years. TWI examined the corrosion fatigue, fracture toughness and static loading properties to determine if the design life could be achieved.

Decommissioning of old platforms

Part of the first major European project on the controlled demolition of disused offshore platforms has been carried out by TWI. This was a joint industry project sponsored by UK's HSE, the EU, and the major North Sea operators and regulatory bodies. This project was to provide technology suitable for engineering practical toppling operations at the end of economic production. It encompassed investigations into structural mechanisms and associated local buckling and fracture.

A purpose-built computer-controlled test rig was constructed at Abington for multi-axial loading tests - to buckle and bend tubular specimens, Fig.4. This rig can produce forces up to 2500kN in axial loading, 1200kN in shear loading and 660kN-m in in-plane bending. Tubular specimens simulating offshore jacket legs were fabricated, with diameters in excess of 0.3m and then crushed and bent through angles up to 45° to simulate toppling.

Remaining life assessment

Refineries and other plant are often reviewed for ongoing operation or when being offered for sale, and it is vital to ensure that sufficient data is at hand to support the business decisions, Fig.5. TWI can provide teams of specialist on-site NDT and metallography experts to provide an independent assessment of major components prior to decisions to purchase and operate existing plant. Data and records relating to construction, materials, operation ( eg temperature and pressure) are combined with the site information to calculate the service exposure of the main items and assess remaining life and future operational viability.

Structural integrity enhancement

Warm pre-stressing (WPS) of pressure vessels has been investigated by TWI since the early 1980s for proof testing and revalidation exercises. Pressure testing to 1.5 times design pressure and elevating the temperature allows deformation to occur more readily around any defect present, whilst the material toughness increases. The deformation has been shown by TWI to increase low temperature fracture resistance. The greater pressures applied in WPS means that the only in-service tests required are regular NDT inspections.

Conclusion

TWI uniquely encompasses an extremely wide spread of disciplines which can be brought together to address the problems of its Industrial Members, now and for their future requirements.