BULK AND CUSTOM BELLOWS
MDC supplies bellows capsules-only for variety of markets and applications. They include supplying expansion joint fabricators who weld-on their own fittings as they serve their geographical areas quickly and efficiently.

Another example is supply of bellows made from exotic materials in critical applications for industrial customers who have the ability to reuse expensive flanges or other types of attachments.

Bellows can be formed from most ductile materials that can be welded by the automatic T.I.G. welding process and result in a homogenous weld structure.
It is imperative that companies specifying and purchasing bellows give thorough consideration to the selection of the bellows material. Due to the fact that media will vary from system to system, and that most media specifications cannot accurately reflect what actually will occur during system operation, it is not appropriate for MDC to make specific recommendations regarding bellows material. If any doubt exists concerning proper material selection for the bellows, we recommend that a metallurgist with the appropriate basic material supplier be consulted. Available bellows materials include:
BELLOWS MATERIAL

T304 SS
T304L SS
T316 SS
T316L SS
T321 SS
Inconel 600
Inconel 625
Incoloy 800
Incoloy 825
Monel 400
Hastelloy C276
Titanium
Laminated(1)
Testable(2)
(1) “Laminated” bellows are used in high pressure, high cycling (requiring flexible bellows element) and highly corrosive environment. Such bellows require a multi-ply construction.

In order to reduce cost, MDC will supply bellows with (ex.) Hastelloy C276 wetted ply and several middle and outer plies made of lesser grade materials such as stainless steels.


(2) Testable bellows provide the user with a guarantee against a catastrophic failure. They are quickly becoming a standard design in chemical and petrochemical industry, where “zero spillage” regulations are mandatory.

Typical testable bellows consists of 2-ply bellows construction. Each bellows is designed individually to withstand system pressure and movement requirements, making it essentially an “expansion joint within expansion joint”. As the sketch below illustrates, the tangent of the outer bellows has an opening with a welded-on coupling.

A monitoring device is attached to the coupling (such coupling can be monitored locally, on site or connected electronically to a central monitoring station). If the inner ply fails, the cavity between plies becomes pressurized with system pressure and the information is relayed to the system operator/inspector.

Since the testable bellows provides the owner with, essentially, another expansion joint, a replacement can wait until the next scheduled shutdown and more importantly avoid spillage, costly clean-up and fines.
In order to properly design and fabricate bellows that will meet your need, please fill out the blank spaces on MDC DWG. 20739 and return to us as an attachment with your Request for Quotation.

Another area of MDC’s bellows supply are the various activities of the OEM market. The applications include:
VACUUM AND HIGH VACUUM TECHNOLOGY Flexible connectors for vacuum components. Spindle sealing in vacuum valves.
HIGH VOLTAGE SWITCHGEAR AND ELECTRICAL INDUSTRY
Vacuum and pressure-proof shielding of conducting elements against atmosphere.
GENERAL ENGINEERING
Bellows assembly replaces gland seal for maintenance- free tightness of the spindle in valves.
MEASUREMENT AND CONTROL
In manometers and automatic control instruments. In thermostats. In flow control instruments. In high pressure valves.
WEIGHT TECHNOLOGY
For the sealing and protection of the electronic modules in weighing scales.
BELLOWS USED AS COUPLINGS
For torque transmission in propulsion and positioning units.
SOLAR TECHNOLOGY
For stress-free couplings of modules in solar panels and solar energy plants.
SHAFT SEALS
For the sealing of rotating shafts and spindles (stirrers).
VOLUME / PRESSURE COMPENSATION
To accommodate volume / pressure variations in hermetically sealed vessels.
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