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Multi Tube Bellows – Nextel®

Introduction of Multi Tube Bellows – Nextel ®

Nextel® Multi Tube Bellows (MTB) are fabricated using high-temperature resistant textiles (up to temperatures of 1370°C or 2500°F) to seal complex gaps in the fired heater or furnace systems. Each MTB is specifically engineered to absorb the multi-axial movement of the tubes whilst still retaining a near perfect seal on the interface between the firebox and the external environment. Depending on the operating temperature, the MTB can be designed and manufactured either filled with ceramic fiber blanket or loose ceramic bulk fiber for adequate heat insulation.


Features of Multi Tube Bellows – Nextel®

  • Made of Nextel® fabric and resistant to high temperatures of up to 1370°C
  • Flexible
  • Custom-made
  • Weather resistant
  • Seals all kind of tube penetrations in roofs, floors, walls for all types of process heaters and reformer
  • Applied in the refining and petro(chemical) industries
  • Can be opened for maintenance and re-installed thereafter
  • Pre-fabricated

Applications of Multi Tube Bellows – Nextel®

  • Furnaces
  • Heaters
  • Ethylene Crackers
  • Crude Heaters
  • Boilers
  • Incinerators
  • Reformers
  • Process Heaters

Comparison Between Multi Tube Bellows – Nextel® and Conventional Method

Multi Tube Bellows Conventional
A flexible tubing-passing sealing system to block all the air ingress Utilizes sliding plates, an insulation padding or an insulation blanket around the tube

Conventional methods are ineffective at sealing off the flow of air through and around the heater. In some cases, seals will block only 10% of the ingressing air.

Design and Installation of Multi Tube Bellows – Nextel®

Firstly, some details are considered such as:

  • Process temperature
  • Required cold face temperature
  • Diameter of tubes
  • Minimum and maximum movement of tubes

The data are then used to design and fabricate MTBs in our factory and shipped to our clients.

Multi Tube Bellows installation is done as follows:

  • Inner fabric of Multi Tube Bellows is installed first.
  • The inner fabric is filled with refractory blanket or loose refractory bulk fiber.
  • Outer fabric is installed.

Depending on the requirements, the fixation method can be varied as follow:

  • Custom fabricated steel plates to support the Multi Tube Bellows onto the furnace plate.
  • Separate (tube by tube) fixing bands.
  • Nextel® tie-cords (fully inserted in the Nextel® fabric topside of the Multi Tube Bellows).

Key Benefits

  • Significant reduction of cold air ingress resulting in improved furnace efficiency.
  • Withstand temperatures of up to 1370°C.
  • Allow unrestricted movement of the tubes while maintaining complete seals.
  • Reduce the possibility of tube damage due to rapid quenching.
  • Block radiant heat loss.
  • Cost effective with very fast payback on investments.
  • Personnel safety enhancement.