These are custom designed big ton variable spring assemblies manufactured for a chemical plant in Brazil. They are fabricated from A-36 carbon steel, with monel rods, nuts and hardware. They measure 18″ L x 26″ H x 26-1/2″ W and are capable of supporting loads up to 60,000 lb. with down travel of .52″. These big tons employ the use of rollers for adequate mobility and are painted to protect against corrosion.
A total of eight big ton spring supports, “mega tons” were designed and manufactured to support two reactors in a power plant weighing approximately three million pounds each. The mega ton pictured incorporated eighteen individual spring coils to produce a load capacity of approximately 602,000 lb. and a spring rate of 112,500 lb./in. It was designed with eight Bronzphite® slide plates that measured 12″ x 12″. The 12″ x 12″ slide plate selection was based upon the ability to position individual squares across the load flange surface while simultaneously providing the total slide plate surface area required to support the operating loads.
By using individual slide plate squares, the fabrication and assembly time was reduced because a standardized mounting procedure could be incorporated and repeated as necessary for each big-ton load flange subassembly. Overall, the slide plates were incorporated into the design to reduce the horizontal forces which would be imparted onto the big-ton spring’s load flange during lateral deflection (movement) of the reactor.
Bronzphite® slide plates, in particular, were selected because these big-tons will be used in a location which will see continuous “cold-to-hot” operating cycles and as a result, the robust nature of Bronzphite® proved more advantageous than other types of slide plates. The other two designs used nine slide plates, one with fifteen individual coils to produce a operating load of 594,000 lb. and a spring rate of 250,050 lb./in. The other design had an operating load of 300,000 lb. and a spring rate of 106,000 lb./in.
Big Ton Spring Supports for a Chemical Processing Plant
A total of 18 big ton springs of various sizes were fabricated from A516 Gr. 70N carbon steel. The big tons were designed in a rectangular configuration in order to match the existing vessel saddle supports and the concrete foundation below the springs. PTFE, 25% glass filled slide plates will be welded on the load flanges to allow horizontal movement in addition to the vertical movements specified. The largest of the big ton assemblies has an operating load of 79,000 lb. with a travel of .706″ down.
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Big Ton Spring Supports with Low Friction Rollers
PT&P fabricated several big ton spring assemblies consisting of two different models for a refinery expansion project in India. The larger model has an operating load of 25,590 lb. and a design travel of .420″ up.
Low Friction Rollers
The smaller model has an operating load of 12,100 lb. and a design travel of .443″ up. The big tons will be utilized to support substantial vertical loads while simultaneously providing a large platform to accommodate axial movement of the piping system across the load flange. Low friction rollers are installed to reduce the sliding friction between the load flange and the bottom section of a pipe shoe.
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