(4) 26.8m (87′-9) X 20 barg (290psig) LPG Spheres

This project consisted of the engineering, procurement, fabrication, construction, full field post weld heat treating (PWHT), and painting of (4) 26.8m (87′-9) x 20 barg (290psig) LPG spheres for Refidomsa at the Terminal Haina in San Cristobal, Dominican Republic. The spheres were designed and built in accordance with the 2019 edition of ASME Section VIII Division 2 Class 2. Due to the large diameter and high internal pressure, the required shell plate was approximately 60mm (2.4in) thick and fabricated from high strength SA738 GrB material. The shell thickness required each sphere to receive a full field PWHT. These were the largest diameter spheres that we have field PWHT. Each sphere has approximately 1100m (3600ft) of weld that was 100% examined by ultrasonic testing. Due to the project location the spheres’ lateral force resisting system was designed to resist hurricane level wind loads of 250 km/h and high seismic loads.

The project is historic in many ways both for the client and for our company – the additional 247,000 BBLs of propane storage is the largest expansion by Refidomsa since it’s inception. This reflects a 57% increase in the refinery’s storage capacity resulting in great benefits for the population which is heavily dependent on propane usage for both domestic and commercial use. The completion of these spheres allows Refidomsa to now have 40 days inventory versus the previous storage of only 14 days.

There were several significant metrics reached during the execution of this project – over 711,000 M/Hrs worked, more than 6,050 tons of steel were erected, just shy of 3 miles of welding installed, over 256,000 ft3 of concrete was poured, and finally an amazing 336 piles were installed. Our Construction Technologies, Process Systems Engineering group, and our Project Management team developed civil engineering designs to provide a safe and efficient work area that accommodated the use of heavy construction equipment. The granular working platform reinforced with geo-synthetic liner provided a system capable of supporting loads up to 13,500 PSF. This robust system was necessary to accommodate the use of a 300-ton crane that was utilized for lifting the 3-plate ground assemblies during the construction of the spheres.

The spheres were erected and welded utilizing regional and local labor with over 80% of the workforce originating from the Dominican.

The project had to overcome the impacts of COVID19 which included a global supply chain collapse, impacts in the number of shipments available, and the reduction of shipping routes and frequencies of shipments.

The project was also challenged with the extreme tropical heat, multiple storms, frequent lightening and hurricane threats. As a result the site conditions were never ideal which led to scheduling challenges throughout the erection, weld pre-heating requirements and other activities including PWHT, painting, and insulating of the spheres.