Steam-Heated Batch Preheat Ovens for Defense-Industry Steel Components

This project was developed for a defense-industry application requiring the batch preheating of large steel components prior to downstream manufacturing steps. Because portions of the customer's process details are proprietary or sensitive, this case study summarizes the requirement at a high level while focusing on the equipment performance and architecture delivered by Precision Quincy.

APPLICATION REQUIREMENT

• The equipment had to preheat steel parts used in a defense-industry application prior to later downstream processing.
• The system description is intentionally generalized to avoid disclosing customer-sensitive manufacturing details.
• The equipment had to provide consistent, repeatable low-temperature preheating for large heavy steel product.

SYSTEM CONFIGURATION REQUIREMENT

• The project required two separate ovens installed side by side.
• The side-by-side configuration supports the customer's throughput and handling requirements.

WORK CHAMBER / LOAD REQUIREMENT

• Required internal work chamber per oven: 120 in W × 96 in D × 168 in H.
• Product height cannot exceed approximately 154 in at the corners.
• Required batch loading capacity: 6,000 lb per batch per oven.

SAFETY REQUIREMENT

• The ovens were required to be designed as Class A units with explosion-proof-rated critical components.
• Each oven includes an interior pull-cord emergency stop located on the left-side wall.
• The work chamber includes sprinklers inside the oven with sealed construction to withstand annual testing.

UTILITY / CUSTOMER-LIMITATION REQUIREMENT

• Required electrical service: 460V / 3PH / 60Hz.
• Customer-limited inlet steam pressure: 15 PSI max; maximum steam inlet temperature: 250°F max.

INSTALLATION / MAINTENANCE REQUIREMENT

• Due to extreme assembled height, the ovens were designed to ship knocked down as flat-packed panel systems for on-site assembly.
• Steam coils are arranged so they can be serviced from a man lift positioned in front of the ovens.
• The tall doors incorporate truck latches to aid door closing due to enclosure size. Final paint finishing is completed on site.

These thermal process requirements were established from the customer's need to preheat large steel defense-industry components in a tightly controlled, low-temperature, safety-focused batch environment.

TEMPERATURE CAPABILITY

• Normal operating temperature: approximately 140°F.
• Maximum operating temperature: 165°F.
• Required workroom temperature uniformity: ±15°F.

PROCESS BASIS

• The thermal process basis is batch preheating of large steel components prior to downstream manufacturing operations.
• The application requires repeatable low-temperature heating rather than high-temperature heat treatment.

HEAT INPUT REQUIREMENT

• Heat source: steam. Installed heat input per oven: 200,000 BTU/hr steam coil.
• Steam supply limited by customer conditions to 15 PSI maximum inlet pressure and 250°F maximum inlet temperature.

AIRFLOW DELIVERY REQUIREMENTS

• Required airflow style: full horizontal recirculation airflow.
• Recirculation airflow basis: 15,000 CFM @ 2 in. w.c.

EXHAUST / VENTILATION BASIS

• Exhaust fan: PQ1 exhauster delivering 500 CFM @ 1 in. w.c.; 0.75 HP explosion-proof-rated motor.

SAFETY / CLASSIFICATION BASIS

• Oven classification basis: Class A.
• Explosion-proof-rated hardware required for critical in-oven components including fan motors and steam control valve.

To deliver the customer and thermal process requirements for Project 5615, Precision Quincy developed the following equipment concept and architecture.

OVERALL CONCEPT

• Two side-by-side steam-heated single-zone batch ovens for preheating heavy steel defense-industry components.
• Each oven is an independent unit. Combined installed side-by-side width is approximately 330 inches with a 4.5-inch gap between units.

HEATING ARCHITECTURE

• Heat source: steam — 200,000 BTU/hr steam coil per oven.
• Steam inlet pressure limited to 15 PSI max; steam inlet temperature limited to 250°F max (customer-site constraints).
• Steam control uses an explosion-proof 4–20 mA steam control valve.

AIRFLOW / RECIRCULATION ARCHITECTURE

• Airflow pattern: full horizontal airflow.
• Recirculation fan: New York Blower tube axial FP27 fan, A22 size — 15,000 CFM @ 2 in. w.c., 15 HP explosion-proof-rated motor.
• Exhaust fan: PQ1 exhaust fan — 500 CFM @ 1 in. w.c., 0.75 HP explosion-proof-rated motor.

CHAMBER / CONSTRUCTION ARCHITECTURE

• Internal work chamber per oven: 120 in W × 96 in D × 168 in H. Exterior dimensions: 162 in W × 120 in D × 220 in H.
• Shell style: structural steel tubing with interior panel cladding. Wall thickness: 6 inches, mineral wool insulation.
• Interior and exterior seams sealed with RTV — supports annual internal sprinkler testing without equipment damage.
• Truck latches on tall doors to assist door closure; steam coils serviceable from a man lift positioned in front of the ovens.

CONTROLS ARCHITECTURE

• Primary controls platform: Allen-Bradley MicroLogix PLC / HMI in NEMA 4 / IP65-rated enclosure.
• Controls are remote mounted so the main panel is outside the hazardous oven area; field devices at the oven use explosion-proof-rated hardware.

SAFETY / COMPLIANCE ARCHITECTURE

• NFPA 86 Class A classification. Explosion-proof-rated: recirculation fan motor, exhaust fan motor, and steam control valve.
• Interior pull-cord E-stop on the left-side wall of each oven. Internal sprinkler coverage in each chamber.

SHIPPING / INSTALLATION ARCHITECTURE

• Equipment is designed to ship knocked down as flat-packed panels due to the extreme overall height.
• Final assembly and paint finishing are completed on site.