Patuxent Naval Air Station, TC-7 Catapult

High Pressure Steam Boiler Replacement

Contract Value: $3,378,000
Contract Type: Design Build

Project Date: May 2008
Compeletion Date: November 2009

ACI was contracted by the Navy Engineering Command (NAVFAC) through a design/build contract to replace the Steam Generation System for the TC-7 Catapult at the Naval Air Station Patuxent River (PAX). ACI partnered with Leach Wallace Associates Inc (LWA) for consulting engineering services and construction management services. LWA provided ACI with a Concept Report for the project and a complete set of stamped Mechanical and Electrical Drawings. ACI's Electric Division was utilized to perform the electric on this project.

The Naval Air Station at Patuxent River is one of only a few installations throughout the world where the Navy can run performance tests on Aircraft Carrier Catapult Operations on a land based system with flight testing resources and engineering support resources that would not necessarily be available on an Aircraft Carrier docked or at sea. This land based system “TC-7 Catapult Operations” consists of the Catapult System operated and maintained by the Navy and the Steam Generation system operated and maintained by civilian personnel.

The project progressed in several phases. The design phase lasted over six months as ACI and LWA worked closely with the boiler operators and plant support personnel to make sure the functionality of the new system would meet and exceeded the functionality of the existing system and to improve on the performance of the existing system where possible.

The first construction phase included replacement of the existing boiler feed system with a completely new boiler feed system. With field prefabrication of the mechanical work and just-in-time delivery of the equipment, the new system was operational in just over six weeks once ACI was granted permission to begin demolition. New equipment installed included one Watts 909 Backflow Preventer, one Kansas City Tank Car Type Deaerator to match the boiler capacity, two Carver RS9 13-Stage Horizontal Ring Section Pumps with over 1000-psig head capability, two Aurora Horizontal End Suction Booster Pumps to provide consistent suction pressure for the larger feed pumps, one Water-Eg custom Resin Softener System and all the associated pipe, valves, fittings, trim, electrical systems required for a complete installation. ACI elected to provide soft start capabilities for the 75-hp 3500-rpm boiler feed pumps to reduce energy consumption at startup and to extend the life of the pump motors. ACI also elected to provide a closed loop bearing cooling system to reduce waste water flow.

The second construction phase included the replacement of the first of two existing 1950s Foster-Wheeler D-Type watertube package boilers with the first of two new 2009 Babcock and Wilcox D-Type FM9-52 watertube package boilers. The new boilers were designed to match the 26,000-pph capacity of the existing units. Each boiler is rated for a maximum working pressure of 825-psig with a normal operating pressure of 690-psig at 750-degrees F. Both boilers are equipped with superheaters to provide dry steam with over 200-degrees of superheat to prevent condensate slugs that would develop in saturated steam with the excessive load swings that are experienced as part of normal operation. Each new boiler was equipped with a new factory mounted Powerflame Vector burner with 33,600-MBH oil input and propane pilot ignition.

While ACI crews worked to prepare the existing boiler for removal, B&W worked to complete the new boiler construction at their factory in West Point, MS. The schedule was coordinated to have a 300-ton crane rig the existing boiler in one piece (110,000-lbs) and set the new boiler (75,000-lbs) on the same day as it arrives from Mississippi. Before any rigging activities on base could occur ACI was required to coordinate with the Federal Aviation Administration (FAA) for approval and base flight operations so a Notice to Airmen or NOTAM could be issued.

Once the first new boiler was set and the roof hatch was replaced and sealed ACI proceeded to prepare the unit for operation. One new Twin City BCS SWSI Induced Draft Fan was installed with a new ABB Variable Frequency Drive. ACI installed a lower drum heating coil to reduce startup stress and operator overtime for startup operations and shutdown operations of the new unit.

All new ASME code welds were self performed with internal QC supervision and Third Party final inspection. MDE fuel burning permits were obtained.