Nuclear/Non-Nuclear Fabrication and Modular Construction
HII Mechanical’s capabilities include the fabrication of tanks, pressure vessels, structural, shield panels and piping assemblies (pipe fabrication). Our capability ranges from individual components to fully outfitted equipment skids and complex modules. We have extensive experience working to AWS, ASME; nuclear and pressure vessel in government and military (DOD & DOE) requirements. We also maintain certificates of authorization from ASME and the National Board for fabrication, modifications, and repair including U, N, NB, NPT, NA, NS, R, VR and NR and are NQA-1 compliant.
Our products can be constructed from carbon steels, low alloy and high alloy steels, super alloys and other weldable material. Components and modules are fabricated at our main facility for easy shipping and transportation. Larger fabrications can be manufactured at our high bay facility or at the installation site. We incorporate photogrammetry and sophisticated dimensional control techniques such as laser scanning to verify compliance and simplify the installation process.
We offer our customers turnkey service with the capability for design, fabrication, testing, and installation. We excel on complex, one-of-a kind fabrications requiring stringent quality control.
Example: DOE High Level Liquid Waste Vitrification Melter
This 3,500 gallon pressure vessel was built for the vitrification of liquid high level radioactive waste with glass. This vessel has a 2 1/2” thick,T304L stainless steel shell with 15 psig internal pressure and 150 psig in the water jacket. The vessel was machined on the inside diameter, including the radii of the top and bottom heads. The tank was mounted in a stainless steel frame with instrumentation, electrical heating elements, process piping and connection ports for robotic interface. This project was completed and delivered to a Department of Energy site in 2011.
Example: Western Refinery 55,000 Gallon Blow Down Tank
The Blowdown Tank was designed and fabricated by HII Mechanical in accordance with the ASME Boiler and Pressure Vessel Code, Sec VIII, Div 1 for unfired pressure vessels. The 55,000 gallon tank is 11’ x 60’ with a design pressure of 50 psig and full vacuum with a temperature of 800 degrees F. The shell plates (five sections) were rolled, edge prepped, and welded at HII Mechanical’s site. Radiography requirement was 100%. The vessel was transported to the refinery where the nozzles and saddle supports were fabricated and installed on the vessel. A hydrostatic test was performed at the client’s site and the exterior painted. Final acceptance of the new vessel was completed by our Authorized Inspector and the new vessel was “U” stamped.
Example: DOE Confinement Vessels
HII Mechanical fabricated six Confinement vessels for the DOE which were used in photographing the characteristics of high energy explosions. The vessels were built to ASME and naval standards using a special high strength, low alloy material. HII Mechanical developed and qualified the unique weld procedures, welded the vessels and performed all machining.
Example: Commercial Nuclear Structural Fabrication: AP1000 Dry Shield Building
Vogtle Electric Generating Plant and V.C. Summer Nuclear Station have both begun construction of two (2) nuclear power units using the AP1000 technology, which uses a simplified, innovative and effective approach to safety and improved operations. One safety feature of this technology is the Dry Shield Building, which provides additional protection to both the power units and the environment. The Safety-Related (SR) dry shield building is a modular ASTM A572 steel shell design with complex internal and external structural features designed to support the adjacent Auxiliary building roof and wall attachments. The shield building also includes air inlet piping to provide natural convection air currents to the cool the steel containment vessel. This project is scheduled to complete and deliver to Vogtle and V.C. Summer in 2018.
HII Mechanical is unique in that it maintains the capability to provide welding services for both military and commercial customers. We have welding procedures qualified to NAVSEA Technical Publication 248 for ship structure and piping/machinery/pressure vessels. Our procedure base also includes numerous procedures qualified to ASME IX for commercial applications.
Our knowledge of the AWS Structure Welding Code (AWS D1.1) allows us to fit, weld and NDE a wide variety of structures with competency and to the highest quality standards. HII Mechanical welders are qualified for flux core and gas metal arc welding of carbon and low alloy steels.
HII Mechanical maintains expertise in the following welding processes:
•GTAW (gas tungsten-arc) including pulse GTAW
•Orbital and fixed head GTAW for mechanized welding of piping
•GMAW (gas metal-arc) semiautomatic and mechanized
•Pulsed GMAW for out of position welding, semiautomatic and mechanized
•SMAW (shielded metal arc)
•FCAW (flux core) semiautomatic and mechanized
•SAW (submerged arc)
•Examples of base materials qualified include: •Carbon Steels
•High strength low alloy steels (HY-80/100,HSLA-80/100)
•Austenitic, martensitic, ferritic and duplex stainless steels
•Nonferrous metals (NiCu, CuNi)
•Inconels (600,625, Hastelloy 276)
HII Mechanical has welding engineering and welding metallurgy expertise on staff that can assist you in resolving your most difficult welding problems.
HII Mechanical utilizes a proprietary weld record management system that streamlines the weld record process and protects final record quality. This system also improves the overall cost performance by reducing the time required to record a weld to mere seconds with nearly flawless accuracy. The system can provide our customers with a single report identifying all the welds with the inherent critical data or with a highly reliable report for each weld. This system, when utilized, saves our customers countless hours of administrative processing time over the standard ‘wet’ record process.