Furnace Applications – Spring Supports, Expansion Joints & Furnace Seal Bags

November 9, 2021

Ptp furnace application products

An industrial furnace, also known as a direct heater or a direct-fired heater, is a device used to provide heat for an industrial process. Furnace designs vary as to their function, heating duty, type of fuel, and method of introducing combustion air. Heat is generated by an industrial furnace by mixing fuel with air or oxygen, or from electrical energy. The residual heat will exit the furnace as flue gas. Types of industrial furnaces include batch ovens, vacuum furnaces, and solar furnaces. Industrial furnaces are used in applications such as chemical reactions, cremation, oil refining, glasswork, metallurgy, mechanical engineering, chemicals, ceramic, and building materials. Industrial furnaces using fossil fuels are characterized by heat losses from flue gases with a temperature of 500°C and above.

PT&P supplies many products that are well-suited for furnace applications. The first category we’ll take a look at is Engineered Spring Supports. We size furnace springs the same way as we would for a conventional variable or constant spring support. Construction may include a welded design instead of bolted and custom nameplates with the test data and ID tag. Most furnace spring supports are coated with red oxide primer to avoid potential hazards when exposed to high temperatures.

Ptp furnace application variables in service combined

PT&P specially designed and fabricated hundreds of altered Type A Variable Spring Hangers in order to accommodate the special travel and spring rate needed to support the furnace tubes of a hydrogen reformer in Venezuela. In order to accommodate customer-specified travel and spring rate, modified spring coils were required. With a travel of 8-7/8″, the variable spring hanger casing lengths were increased from the standard size of 32″ to over 6′ long. The calculated spring rate is 79 lb/sq in for an operating load of 2,804 lb. and an installed load of 3,505 lb. The housings are coated with heat-resistant paint, which protects the spring coils from corrosion and high temperatures in the furnace area.

Expansion Joints are not installed inside furnaces due to the extremely high temperatures of the environment and the piping system. Expansion joints will typically be found on the duct work and in the piping coming in and out of the furnace. In the last six months, we have shipped over 40% of our expansion joint jobs in less than 2 weeks to meet customer project deliverables.
Fabric expansion joint application

Fabric Expansion Joints that are in-service near furnaces, typically include a 3-layer belt consisting of Silicone, Fiberglass, PTFE, and Mineral Wool Insulation. The configurations are either round, rectangular or square as seen in the examples below.

Ptp furnace application products

Furnace Bags are used to seal high-temperature tubes that penetrate the furnace floor. The furnace bag consists of multiple layers of flexible, flame and heat resistant, impervious fabric designed to operate from start-up to high-temperature design conditions. The bag will expand and contract with the varying furnace temperatures.

Furnace Bag

Stainless steel clamps or band straps connect one end of the pipe that goes through the penetration opening and the other to another sleeve in the furnace floor. A tapered steel coil is installed around the conduit inside the bag to prevent the fabric from collapsing inward during vacuum conditions. PT&P’s standard furnace seal bag is nickel reinforced, with a special coating that reduces airborne fibers and increases tensile strength.

 

Furnace application diagram

Variable Spring Supports for a Furnace application at an Ammonia Plant

August 7, 2017

Variable Spring Supports for a Furnace application at an Ammonia Plant

Type: Variable Spring Supports
Material: Carbon Steel | Red-Oxide Primer | 304 SS
Design: 3,000 lb./in.
Testing: Load Test

PT&P custom designed variable spring support assemblies for a furnace application at an ammonia plant. The furnace springs are fabricated from carbon steel and painted with a red-oxide primer to help prevent corrosion. The pipe clamps are fabricated from 304 stainless steel. They are designed to support a cold load of almost 3,000 lb./in. while operating in an area where temperatures are higher than ambient. There were a total of 173 assemblies fabricated for this project, 152 variable hangers, 3 constant spring supports, 6 ball joint rigid struts, and 12 rigid rod hangers. Special load tests were performed prior to shipping.

Variable Spring Supports Designed for a Furnace in Trinidad

February 21, 2017

Variable Spring Supports Designed for a Furnace in Trinidad

Type: F-Type Variable Spring Supports (Furnace Springs)
Material: Carbon Steel | Red Oxide Primer
Design: Movement: 1/2 “| Load: 398 lb. | Spring Rate: 84 lb./in.
Testing: Standard Spring Rate & Calibration Tests

PT&P designed and manufactured these F-Type variable spring supports for use in a furnace at a facility in Trinidad. We manufactured these furnace springs for an operating load of 398 lb., a movement up to 1/2″, and a springs rate of 84 lb./in. They are fabricated from carbon steel with a red oxide primer coating to protect against corrosion. Customer specifications required a modified, installed height, while maintaining the spring rate, operating load and install load. In order to accomplish this, PT&P designed, manufactured and attached, to each spring, a pedestal to accomplish the increased installed height.

Variable Spring Supports Designed for a Furnace Application in Oklahoma

September 26, 2016

Variable Spring Supports Designed for a Furnace Application in Oklahoma

Type: Variable Spring Supports
Design: 1,765 lb. Load | +/- 5% Spring Rate
Material: Carbon Steel with Red Oxide Primer
Testing: Standard Spring Rate & Calibration Tests

PT&P custom designed variable spring supports for a furnace application at a Nitrogen Facility in Oklahoma. The furnace springs are fabricated from carbon steel and painted with a red-oxide primer to help prevent corrosion. The spring supports are designed to support loads up to 1,765 lb. With a spring rate calibrated to be within +/- 5% of the theoretical value.

300 Variable Spring Supports Designed for a Furnace Application

April 25, 2016

300 Variable Spring Supports Designed for a Furnace Application at a Methanol Processing Facility

PT&P designed and fabricated 300 variable spring supports for use in a furnace within a methanol processing facility in Mexico. We manufactured the ”housing” of these variable springs using seamless pipe (in order to prevent the springs’ coils from rubbing against the ”weld seam” of a standard pipe) so that the exact spring rate (+/- 5%) can be calculated without discrepancies or variations. The reason that an accurate spring rate is important is because furnace springs function as a ”scale” in order to determine the weight of the radiant coils within the unit. These springs are coated with red oxide primer to protect against corrosion. We manufactured these furnace spring assemblies for an operating load of 1,036 lb. and a movement up to 8 1/2″. Each spring is traceable to test data and tagged with its’ unique spring rate along with other standard information use for identification.

Pipe Supports and Expansion Joints for Furnace Applications Webinar

April 14, 2016

This webinar is over, view the recording in the webinar archives

Furnace SpringsJoin us for this Webinar focusing on the unique design aspects of pipe supports and expansion joints operating in furnace applications. See how these non-standard designs impact the overall construction and fabrication processes. Learn the differences between standard supports and those specifically used in furnace applications. View the in-depth testing processes and learn what to watch for during inspection and maintenance intervals.

The featured presenter, Jerry Godina has over 15 years experience as a pipe support designer and manages PT&P’s engineer training development program. He also inspects existing supports, consults on site remediation projects and oversees installation on a regular basis.

 

Variable Spring Supports Custom Designed for a Furnace Application in an Ammonia Plant

July 28, 2014

Variable Spring Supports Custom Designed for a Furnace Application in an Ammonia Plant

PT&P custom designed variable spring supports for catalyst tubes in a furnace for an ammonia plant in Canada. The furnace springs are fabricated from carbon steel and painted with a red-oxide primer to help prevent corrosion. This project required special coils that were within +/- 5% of the calculated spring rate. Over 245 springs underwent calibration test prior to shipment. PT&P has been supplying furnace springs for over 25 years and can customize them to meet your specifications.

112 Custom Variable Springs Designed for a Furnace Application in Venezuela

December 15, 2013

112 Custom Variable Springs Designed for a Furnace Application in Venezuela

112 custom variable springs designed for a furnace application for an oil refinery in Venezuela. The furnace cans are designed from carbon steel and painted with red oxide primer to prevent corrosion when exposed to high temperatures. The sizes of these figures PTP-6 and PTP-8 range in length from 25″- 39″, with a total travel of 0.1″- 1.821″ and loads varying from 430 – 681 lb. A load test to confirm the spring rate was conducted on each assembly prior to shipment.

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