Manway Assemblies

Contents:
Elliptical Manways
    Yoke & Bolt
    Clamp Bolt
    Bolt Plate Manways

Elliptical Rings
Flat Machined Covers
Gaskets
    Teflon
    Buna-N  Buna-S
    Black Neoprene
    Spiral Wound
Elliptical Manways

    Elliptical manways provide reliable, low cost access to pressure vessels.  Our manways are self-energizing, or self sealing, for an unlimited range of internal and external pressure applications.  Manways are available in 304, 304L, 316, and 316L SA-240 stainless steel and several grades of carbon steel. 
    All elliptical manways are constructed of four basic parts: the elliptical ring, the cover, cover hardware, and the gasket.  The elliptical ring is a piece that allows the yoke to hold the cover in place when the tank is de-pressurized.  Various cover and cover hardware configurations change the use and product name for the manway.  Gasket material varies from application to application.  Our manways are self-energizing, meaning that the manway is sealed by compression from the interior of the vessel to which the ring it is welded. 
    We offer two basic types of manways: yoke & bolt and clamp bolt, as well as bolt plate manways for severe conditions.  In addition, flat machined covers are available for high pressure applications and numerous variations of both manways to meet specific design criteria.
Two-Part Units
    A complete manway unit involves a specific type of sealing configuration (yoke & bolt, clamp bolt, or bolt plate) and an elliptical ring in the correct size.  Information listed for each type of manway refers to the sealing configuration, the cover, cover hardware, and gasket.  In order to complete a manway assembly, an elliptical ring is necessary.  Information on elliptical rings is listed separately.  For ordering purposes, a complete manway should be thought of as a two part unit: sealing configurations and ring.
Seamless Elliptical Rings
    All elliptical rings available are seamless.  Seamless rings provide superior quality and strength to our manways.  Seamless construction ensures uniformity and consistent performance over years of service.

Yoke & Bolt Manways  (standard applications)
Click here to view standard yoke & bolt manway dimensions and ratings.
The yoke & bolt manway provides the most economical pressure vessel access.  As a self-energizing unit, yoke & bolt manways require positive internal pressures of at least 50 psi to achieve a seal.  The standard yoke 7 bolt unit consists of a carbon steel ring, a pressed steel cover (SA-285-C or SA-516-70 for covers), one or two steel yokes (depending on type) with bolts and a gasket.  Rings and cover are available in other materials

Clamp Bolt Manways  (vacuum applications)
Click here to view standard clamp bolt manway dimensions and ratings.
Patented clap bolt manways are a low profile alternative to the yoke & bolt manway as well as a reasonably priced unit for vacuum applications.  The standard assembly consists of a carbon steel ring, pressed steel cover (SA-285-C), two steel clamps with bolts, and a gasket.  Rings and covers are available in other materials as are the gaskets.  These manways can be ordered with four, instead of the standard two, clamp bolts.  Rings are available in ¾ X 3 or ¾ X 4 wall sizes.



Bolt Plate Manways  (for applications with pressures over 1000 psi)
Bolt plate manways are used for high pressure and vacuum service, in applications requiring hard gaskets (solid jacketed, spiral wound metal) or where severe external pressures exist.  They can be designed for an unlimited range of internal and external pressures.  The bolt plate sealing mechanics maintain constant sealing force, which makes these manways a good choice for vacuum applications.  A standard bolt plate manway consists of an elliptical ring, a flat machined cover, a bolt plate, six stud bolts with hex nuts, and a gasket.  The sealing mechanism works through the mechanical force applied by the bolts between the cover and the bolt plate (see illustration).
Bolt plate manways are custom designed for specific applications.  Contact us to assist with details.

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Elliptical Rings

Click here for required elliptical ring depths for different sized vessels and manways. 
    All of our elliptical rings are seamless, no welding is used in their manufacture.  Each ring is formed, hot sized, and one edge faced for superior gasket sealing.  Our seamless elliptical rings are available in a wide range of sizes and thicknesses, and are furnished to SA106-Gr.C unless otherwise specified.  Rings made from stainless steel or other metals are available.

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Flat Machined Covers  (for applications with pressures over 600 psi)


    Flat machined covers are made for pressures greater than basic yoke & bolt or clamp bolt manways can tolerate.  These covers are available in standard thicknesses or in custom specified thicknesses that allow for an unlimited range of pressure / temperature conditions.  Designed for use with yoke & bolt manways, flat machined covers can be manufactured in a wide range of materials.  Standard covers are made of carbon steel (SA105 or SA-350-LF2).

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Gaskets

    The Rasmussen Company offer gaskets in a wide variety of materials for use with manways.  One versatile material is teflon**.  Teflon gaskets provide superior performance and are an ideal substitute for asbestos.  Below are descriptions of available gasket materials:
 
Teflon
Teflon gaskets are strong and tough, yet soft, allowing them to conform to any surface.  They compress to a thin, wide ribbon under pressure.  Teflon gaskets do not deteriorate with age, are unaffected by many chemicals, tolerate temperatures up to 650° F and pressures of 3000psi, and will not contaminate flow products.  In addition, teflon's non-stick characteristics allow easy manway opening.

Buna-N  Buna-S
This is a well known plastic material that can be used in environments up to 250° F.

Black Neoprene
This is a synthetic rubber gasket material useful for certain process applications.  It can tolerate temperatures up to 250° F.

Spiral Wound
This is a flexible metal gasket material for use in high pressure, high temperature situations.

**Teflon is a registered trademark of E.I. DuPont de Nemours & Co.

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Please contact us with any inquiry!

Rasmussen Company, Inc.

338 Oakton Avenue
Pewaukee, WI  53072-3400
United States

Phone:  800-558-0575 (in the U.S.) or 262-695-3320
Fax:  262-695-7545
Email: rascoinc@gmail.com