Bonnet Types

Standard Bonnet

Valtek Sulamericana generally manufacture bonnets for the GLS, Series control valves with the same material as the valve body, withstanding operating temperatures from –28º to 400ºC, depending on the packing material. See temperature limits for different packing
materials in the Packing & Guiding page.



Extended Bonnet

Extended bonnets protect the packing against excessive heat or cold that could affect the performance of the control valve, and are available on Valtek Sulamericana’s GLS Series Control Valves. Extended bonnets manufactured by Valtek Sulamericana with carbon steel can be used in operating temperatures from –28º to 426ºC, depending on the selected Packing material. Extended bonnets manufactured from 304 or 316 stainless steel are able to operate in temperatures from –100º to 815ºC, also depending on Packing material. Alternative materials are also available on request depending on process conditions. See temperature limits for different packing materials in the Packing & Guiding page.



Cryogenic Bonnet

Valtek Sulamericana’s Cryogenic Bonnet for the GLS Series control valve allows a small portion of the vaporised cryogenic liquid to remain trapped inside the bonnet, creating a suitable temperature gradient that protects the packing. It is usually made from 304 or 316 stainless steel to withstand low temperatures down to –253ºC. For this type of construction, the standard material of the bonnet flange and bolting is stainless steel.



Bellows Seal Bonnet

The Bellows-pack Bellow Seals Bonnet offering from Valtek Sulamericana makes the GLS Series control valve the right choice whenever the requirement for zero fugitive emissions to the atmosphere is to be achieved. This seal is generally specified for process fluids that are considered toxic or lethal. The Bellows-pack configuration, is a one-piece extended bonnet equipped with a set of sealed chambers capable of high cycling capacity, along with a double packing system. For this configuration the bonnet is manufactured in the same material as the valve body, with the Bellows-pack manufactured in special alloys.


Bonnet Flange & Bolting Specifications

Bonnet Flange (Standard) Bonnet Flange (Optional) Bonnet Flange Studs & Nuts (Standard) Bonnet Flange Studs & Nuts (Optional)
Carbon Steel Stainless Steel1 or same material as body ASTM 193 Gr. B7 / ASTM A194 Gr 2H2 304 or 316 Stainless Steel1,3, & 4

1Optional materials are always necessary when exceeding indicated temperature limits.
2Operating temperature from —28° to 426°C, provided that body limits are respected.
3Operating temperature from —253° to 815°C, provided that body limits are respected.
4Other materials upon request, depending on operating conditions and design criteria.


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