ACCO was chosen as the HVAC contractor for the retrofit of Space Launch Complex 6 (SLC-6) at the Vandenberg Air Force Base. SLC-6 had been unused since the space shuttle disaster in 1986.

The retrofit of SLC-6 was done to accommodate Boeing’s Delta IV rockets as part of the Department of Air Force’s Evolved Expendable Launch Vehicle (EELV) program.

Most of the equipment and system installation was done per plans and specifications. Some of the work, however, was done on a design/build basis. This included:

• Duct Construction – Ducts feeding the payload section and vehicle sections were stainless steel and had to be designed for 80” static pressure. SMACNA industrial manuals stop at 50” and ACCO had to develop new duct construction standards that considers 85 mph thrust/wind loads, vertical buckling loads, expansion anchorage, seismic and other loads.
• Supports – Supports had to be designed for the ducts and piping and all specialty components. Most supports were welded steel sections. Expansion guide and anchor supports had to be designed and built by ACCO.
• Steam Humidification – ACCO informed Boeing that the only way to obtain the tight tolerances demanded by the satellite (payload) customers was to move the humidification coils downstream of the blowers. This required a new steam generating and distribution system with cascade controls due to the long distance from the steam humidifiers to the point of delivery.

ACCO obtained HEPA filters in housings capable of withstanding the 80” static pressure. Air traveled hundreds of feet from the HEPAs to the point of delivery at cleanliness levels up to Boeing’s “Class 5000” requirements. The tests indicated cleanliness levels in the class 100 range and better. The duct had to be installed clean and the results paid off by not having to dismantle and re-clean.

Special flex duct was utilized to go between the fixed umbilical tower (FUT) and the swing arms which connect the rocket and then swing away at launch time.

Project Team

• Owner - Boeing
• Prime Mechanical Contractor - Industrial Construction, Inc.
• General Contractor - Clark Construction
• Engineer - Raytheon/WGI