Many GASCO pipelines cross major highways in Abu Dhabi through concrete culverts (lengths varying from 50 to 125m). Some culverts are in severely deteriorated condition and required immediate replacement. Collapse of culvert(s) may lead to failure of the pipeline resulting in Loss of Containment, environmental degradation and potential risks to personnel/neighbourhoods. This paper presents a techno-economical solution as an alternate to the repair/replacement option for safeguarding the integrity of the pipelines. GASCO identified four severely deteriorated concrete culverts which are protecting 6nos vital oil/gas pipelines, for major repair/replacement. Performing the repair/replacement of these culverts pose challenges due to access restraints, traffic obstructions/diversions, massive civil works, risk of working in the live gas pipeline vicinity etc., with huge overall estimated cost and more than two years execution time. GASCO studied/explored different options including the repair/replacement of existing culverts and ended up with selecting the option of flooding the culverts with a self-compacting mixture of sand and water using specialized pumps which can satisfy/meet the technical, commercial aspects and extend the remnant life. Detailed study was carried out to verify the various technical aspects and evaluate the methodology, with data collection of existing pipe sizes, pipeline wall thicknesses from pipe condition inspection reports, vehicle loads, vibration measurements due to vehicle movements at pipe depths and desktop evaluation of data. The existing pipelines wall thicknesses were checked for Barlow stress (Hoop stress), Circumferential Stress, Longitudinal Stress, Radial Stress and Fatigue check for Girth & Longitudinal Welds considering the overburden loads of earth/sand fill, vehicle cyclic load and internal pressure/temperature and found adequate. Methods of construction and different materials for filling were explored. In some culverts, there was not adequate headroom for people/ equipment access. The method of pumping sand (using special pumps) and compaction of each sand layer by water flooding was found to be the most suitable option in terms of technology, local equipment availability/easy mobilization, locally available filling material, reduced risk of working in the vicinity of live gas pipes, etc. The solution was successfully implemented for the four culverts (each 60m long) across the busy Abu Dhabi – Al Ain highway at Mussafah, in Sep-2015, within 2 months duration and resulted in a huge cost saving of AED 38millions. The followed approach is a long term solution that can be executed by the in-house resources of maintenance team with some support from local contractors (for pumping facilities, etc.) and it also eliminates the future maintenance cost. This solution is first of its kind that was implemented among ADNOC group companies and can be shared with/ adopted by other companies having similar facilities to benefit from the cost optimization & other advantages.

Proper functioning of the drainage system in oil and gas plant is vital for uninterrupted operation of the plant facilities. Among the various drainages, oily water drainage system is critical with high risk considering its hydro carbon content and accumulation of explosive vapours due to improper functioning of any components in the system. This paper presents some of the shortcomings in the design/arrangement/maintenance of the different elements and the improvements to avoid accidents. The drainage types in GASCO plants are Clean Water Sewer, Sanitary Sewer, Oily Water Sewer (Accidentally Oil Contaminated / Continuously Oil Contaminated) and Chemical Drains. One of the unforeseen risks has caused an explosion in an existing oily water sump inside the process area. The sump was of concrete construction and the cover slab was blown up resulting in considerable damages to the surrounding pipes/support. There was no injuries to personal. The root cause analysis of the incident was done and a study carried out for a safety review of oily water drainage system at all plants. A study was carried out to identify possible hazards/design deficiencies of the oily water drainage facilities and recommend measures for rectification and risk mitigation. The study identified that the lines are placed in slope & mainly "run dry" after use, liquid seal not available in some manholes causing HC vapour upstream movement, the manholes/sumps are closed, vent pipes size is small and some are blocked. These lead to accumulation/formation of hydrocarbon mixture inside closed sump, ignition by overheating of the pump installed over the pit and subsequent explosion. Recommendations for existing system include regular flushing of the lines with water to ensure transport of oily effluent & maintain liquid seal, regular removal of the floating hydrocarbon liquid from pits using vacuum truck, open up the manholes and use grating covers, provide self-skimming bucket where feasible, etc. Additionally, for new facilities it is recommended to lay the pipes horizontally to ensure liquid seal, provide turn-up elbows to reduce hydrocarbons accumulation in manholes, provide oil skimming/baffle wall in oil/water sumps, use classified equipment, carryout proper maintenance, etc. The sump was reconstructed with the new design, which is now functioning well and the recommendations are being implemented in existing facilities and in all new projects. The proposed improvements for the existing system as well as adopting the recommendations in future new drainage system can ensure the prevention of possible explosions and thereby reducing the related hazards to plant facilities/operations. Sharing of the related information among the international companies having similar facilities increases the awareness about such hidden sources of explosion in a drainage system and related pro-active mitigating measures.

Among the various drainages in oil and gas plant, oily water drainage system is critical with high risk considering its hydro carbon content and accumulation of explosive vapours due to improper functioning of any components in the system. This paper presents some of the shortcomings in the design/arrangement/maintenance of the different elements, learnings from an explosion incident and the improvements to avoid accidents. The drainage systems in ADNOC Gas Processing plants are Clean Water Sewer, Sanitary Sewer, Oily Water Sewer (Accidentally Oil Contaminated / Continuously Oil Contaminated) and Chemical Drains. One of the unforeseen hazards has caused an explosion in an existing oily water sump inside the process area. The sump was of concrete construction and the cover slab was blown up resulting in considerable damages to the surrounding pipes/support. There was no injuries to personal. The root cause analysis of the incident was done and a study carried out for a safety review of oily water drainage system at all plants. A study was carried out to identify possible hazards/design deficiencies of the oily water drainage facilities and recommend rectification measures. The study identified that the lines are placed in slope & mainly "run dry" after use, liquid seal not available in some manholes causing HC vapour upstream movement, the manholes/sumps are closed, vent pipes size is small and some are blocked. These lead to accumulation/formation of hydrocarbon mixture inside closed sump, ignition by overheating of the pump installed over the pit and subsequent explosion. Recommendations for existing system include regular flushing of the lines with water to ensure transport of oily effluent & maintain liquid seal, regular removal of the floating hydrocarbon liquid from pits using vacuum truck, open up the manholes and use grating covers, provide self-skimming bucket where feasible, etc. Additionally, for new facilities it is recommended to lay the pipes horizontally to ensure liquid seal, provide turn-up elbows to reduce hydrocarbons accumulation in manholes, provide oil skimming/baffle wall in oil/water sumps, use classified equipment, carryout proper maintenance, etc. The sump was reconstructed with the new design, which is now functioning well and the recommendations are being implemented in existing facilities and in all new projects. The proposed improvements for the existing system as well as adopting the recommendations in future new drainage system can ensure the prevention of possible explosions and thereby reducing the related hazards to plant facilities/operations. Sharing of the related information among others having similar facilities increases the awareness about such unseen sources of incidents in a drainage system and related pro-active mitigating measures.

Plant buildings that housing critical equipment and/or manned are generally sited at safe distances from potential explosion sources of process facilities or designed considering anticipated blast pressures during initial construction. However, addition of new process facilities during plant expansion generates new potential explosion sources, blast overpressure range of which exposes some existing facilities to new risk. This paper discusses the approaches followed to assess risks and mitigation measures employed to ensure safety of occupants and integrity of assets. Quantitative Risk Assessment forms the basis for blast considerations on buildings, wherein potential Vapor Cloud Explosion scenarios are identified, and blast overpressure are quantified in the form of contours on plot. Buildings located within blast contours are identified for blast-resistant design to ensure occupant's safety and facilitate safe shutdown of process units during explosion. Whenever Plant expansion is envisaged, a fresh QRA is carried out with potential explosion scenarios. For the explosion analysis, a detailed computer model of plant is generated to closely simulate the congested vulnerable sites and accurately predict blast overpressure, thus optimizing the impact on existing buildings. Based on outcome of the analysis, existing buildings requiring additional blast protection are recognized. In new set-up, process related buildings such as control rooms, OMS, IES etc. are located closer to process area and non-process buildings are sited away from process area. Buildings are designed to resist normal loads along with/or without estimated blast loads based on its location, occupancy and function. During plant expansions, due to space/operational constraints, some new process facilities get closer to the existing buildings. This imposes increased/additional blast load and causes risks to occupants, equipment and building integrity. Hence a comprehensive assessment needs to be carried out and mitigation measures explored. A study was done to assess the impact of such a scenario in one of the gas plants. The study found that some buildings which were originally designed for normal loads are now being subjected to certain intensity of blast loads. The criticality of the building was assessed considering the occupancy level and functional requirement of buildings. The inherent capability of buildings to withstand these additional loads were also evaluated. Based on the study outcome, different mitigation measures such as reducing occupancy, relocating critical items, retrofitting of structure, etc., were explored and feasible options recommended. Assessment of existing buildings for blast overpressure has gained importance in recent years due to steady expansion of old plants. The paper presents the approach followed in the study for such situations and effective measures that can be taken without compromising the safety of the personnel. These requirements are common for similar expansion projects and can be adopted across the industry.

"Optimization" or "Fit for Future" is the new norm for any industry in this competitive global environment. To encounter the challenges and to embed 100% HSE, efficiency, performance and profitability in operation, maintenance and new constructions, there is an urgent necessity to review and update existing design and construction specifications. This paper summarizes the approaches, systems and examples of major updates in about 264 Nos. of multi-disciplinary Design General Specifications (DGS) of ADNOC Gas Processing that are brought under scanner and being revised to realize the strategic/ economic benefits of standardization. In ADNOC Gas Processing, specifications for various engineering disciplines namely, process, automation, control, electrical, static/ rotating equipment, piping/ pipeline, civil/ structural are followed in engineering, construction and maintenance activities. These were developed over years to steer the Company towards unparalleled reliability, operability and integrity. Now, the challenging market demands adaptability, agility and forward thinking with a need to "balance the performance with profitability", without compromising HSE. Hence, a "Lean" approach towards the specifications is emphasized by focusing on cost-saving and value addition in terms of reduced time and enhanced efficiency. Apart from revisions based on latest international codes/ standards, specific attention is given to details by incorporating latest technologies, materials and processes. Best practices and lessons learnt based on direct involvement with Operation, Projects and Supply are being embedded in the DGSs. A set of DGSs were reviewed by external consultants and Company to incorporate the valuable changes. A detailed plan to incorporate the changes was worked out and assigned to disciplines. Major optimization features were addressed in the ongoing studies/ projects with immediate effect. This paper discusses potential areas of optimization and cost savings. A minimum of 15 to 20% cost saving is expected to be realized in adopting the revised specifications in the ongoing and future projects/ studies; more benefits are expected on task completion. Maximum results are obtained by re-visiting the design parameters in the light of latest codes/ standards applicable to all the engineering disciplines. Alternate technologies/ materials contribute to further optimization. Sizing of buildings, equipment and features are addressed in the DGS updates. Operational margin of equipment, stability ratios of the structures and performance of the instruments are scrutinized and brought to an optimal level resulting in overall efficiency. Discipline-wise enhancements and potential cost saving ranges are detailed in this paper. This paper presents "Fit for Future" initiative that has changed the organizational culture and reflects effectively in all activities across the Company. As all the technical activities are based on DGSs, update plan and potential cost realization are the main drivers for enhancing the performance without compromising HSE. This novel approach of re-visiting the technical specifications in the light of "high efficiency with low cost" can be adopted across other OPCOs and move towards common specifications for ADNOC.