Since 1983, Gulf Marine Maintenance & Offshore Service Company LLC (GMMOS), the high-end steel fabrication division of the VASUDA Group, has been providing equipment and services to the global oil and gas industry. GMMOS has headquarters in Dubai, United Arab Emirates (UAE) and a 35,000 m² fabrication yard in the Jebel Ali Industrial Area 1 in the UAE and at Aktau, Kazakhstan.
The company offers a range of specialized services and equipment, such as pressure apparatus, piping, pipe spooling and skid packages. Its comprehensive offerings include mechanical and process engineering solutions for various sectors. These sectors encompass onshore and offshore environments, marine, shipping, chemical processing, water treatment, desalination, as well as power plant and refinery equipment.
Identifying goals
GMMOS has been working in coordination with a global engineering procurement and construction firm on a large-scale fabrication project for the development of the Shah Gas Field southwest of Abu Dhabi, UAE.
The project includes 31 pressure vessels for multiple purposes and varying sizes with GMMOS providing design, detailed engineering, material procurement, fabrication, inspection, testing, painting, delivery and documentation of the pressure vessels.
Overcoming challenges
A challenge arose because these were low pressure vessels, the thickness required for internal pressures was not sufficient to provide the structural stability needed during operation and hydro-test conditions. Of the project’s 12 largest horizontal vessels, two had an inside diameter (ID) of 6 meters and tan-to-tan length of 29 meters and two had an ID of 5 meters and tan-to-tan length of 25 meters.
By using Aspect Pressure Vessel, GMMOS produced accurate mechanical strength calculations for pressure vessels per ASME BPVC Sec VIII Div-1 Ed 2007 + 09
Addenda and Ed 2010 rules for the design and construction of pressurized boilers and vessels.
“We completed the required calculations faster and produced more accurate output by using Aspect Pressure Vessel,” said Muthalagu Alagappan, supervisor of Engineering Design.
Realizing results
Since the majority of these were sloping vessels, the saddle at the shorter side needed to have enough height so that its moment of inertia (MOI) equaled of exceeded the stiffener rings provided.
Aspect Pressure Vessel provided a saddle design input option called height of web at center, to ensure that the MOI of the saddle was sufficient – where the circumferential stiffener ring was broken – to allow for saddle placement on the vessel.
This type of project with its extremely large vessels, very high diameter-to-thickness ratios and great distances between saddle supports presented a challenge in finalizing the geometry, thickness and location of supports. “By leveraging Aspect Pressure Vessel, we were able to meet all of the project’s requirements and quality standards,” Alagappan said. “This helped ensure a good reference from the client for future jobs.”
