Brush Seals Home > Products
Brush seals for gas & steam turbines
Brush seals are a proven technology in the aerospace and power generation industries, delivering significant efficiency improvements over traditional labyrinth seals.

Cross is a leading innovator and manufacturer of brush seals for new equipment and for performance enhancing projects on existing equipment. Cross brush seals have been in field service applications for countless thousands of hours, delivering sustained performance improvements.

A brush seal contains many thousands of fine wires, forming an effective barrier to flow whilst accommodating shaft excursions, thermal movements and misalignments that would instantly reduce the efficiency of a labyrinth seal.

Cross brush seal design

Welded construction gives flexibility in design and cross section.
Bristles can be any weldable superalloy.
Current materials used are Haynes® 25, Waspalloy® and C276.
Any wire size can be used; current range from 0.05mm to 0.168mm.
Typically 10 to 20 wires through the pack, but any number available.
Accurate control of bristle angle and pack stiffness.
Front and back plate manufactured from any weldable material, including 409, 410 & 304L stainless steel, Inco® 718, Inco® 625, Inco® 909, Haynes® 188, Hastelloy® X and Hastelloy® S.
Material is typically chosen to match the expansion of the housing or to minimise transient closure during operating cycles.
Deep front plate aides bristle stability in high swirl conditions.
Cavities in back plate reduce seal hysteresis and pressure stiffening whilst increasing blow down.

Cross brush seal history

1976 – Cross approached by Rolls Royce to manufacture a brush seal.
1987 – First Cross brush seal test rig commissioned.
1990 – Cross manufactures first brush seal with ceramic bristles.
1990 – First Cross technical paper on brush seals published:
90-2143 Brush Seal Development System, by Ralph Flower.
1990 – Cross designs and supplies first segmented brush seal, use in an aerospace engine. Cross files patent for segmented brush seal.
1994 – Cross starts work on applying brush seals to ground running gas turbines.
1995 – Cross starts work on applying brush seals to steam turbines.
1996 – Cross supplies first brush seal for ground running gas turbine.
1997 – Cross supplies first brush seal for a steam turbine.
2000 – Cross supplies first brush seal with polymer based fibres.
2000 – Cross hot test rig facility commissioned.
2002 – Cross 3D FEA model developed in Adina.
2007 – Inspection of Cross brush seal after 8 years of service in a steam turbine.
2009 – Further enhancement of Cross 3D FEA brush seal model.

Product Summary    
One-piece brush seal rings in diameter sizes from 20mm to 1200mm. Larger diameter sizes supplied in multiple segments.

Operating temperatures up to 600˚C at pressures up to 20bar per single stage of seal.

Shaft surface speeds up to 384 metres/second.

Aerospace brush seals  
First applied to aerospace turbines in the 1970s and now fitted as original equipment on engines manufactured by GE Aircraft Engines, Rolls Royce, Honeywell, Pratt & Whitney and MTU.

Applications include compressor discharge, pressure balance pistons and bearing cavities.

Brush seals for gas & steam turbines

First supplied into this market in 1994 and now supplied for new build and upgrade packages to GE Power Systems, Siemens Westinghouse, Alstom, MHI and Nuovo Pignone.

Applications include compressor discharge, turbine interstage and bearing cavities.

Brush seals for steam turbines  
Applications include bucket tip seals and shaft seals in end packing locations. Pressure drops in excess of 13Bar are being sealed with single stage rings.

Test facilities  
Static test rig
Cross has a number of test rigs to suit 129mm or 190mm bore seals. Most have back pressure capability and easily interchangeable disks. These rigs are very good for quickly gaining information on blow down characteristics at pressures up to 19Bar.
Dynamic test rig
Originally commissioned in 1987 and continually developed, the rig tests a single 129mm or 190mm seal at speeds up to 19,000 rpm and pressure drops up to 9.6Bar. Housings can move radially and axially relatively to the disk centre line. Many different housing and disk configurations can be run for specific applications. Investigation into bristle stability is facilitated by video bore scope with stroboscopic light source.
Hot test facility    
Commissioned in 2000, the hot test facility is designed to simulate the transient operating conditions found in aerospace gas turbines. The control room provides computerised control of speed, temperature and pressure.  
Stiffness checking  

Customised Cross adaptation enables testing of circular and segment seals.
    Click for Animation    
  Copyright © 2011. Cross Manufacturing Company (1938) Ltd. All Rights Reserved. | Disclaimer 
About Us
Contact Us