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According to which material specifications are STRAUB couplings manufactured?
STRAUB-GRIP-L in W2 and W5
STRAUB-METAL-GRIP in W1, W2 and W4
STRAUB-PLAST- and -COMBI-GRIP in W2 and W4
STRAUB-FLEX and -OPEN-FLEX in W1, W2 and W5

Can STRAUB provide stepped couplings?
Generally STRAUB-FLEX couplings are able to compensate diameter differences of up to 27 mm (depends on the diameter). On request bigger diameter differences are possible with STRAUB-STEP-FLEX.

Is STRAUB selling only through traders?
Yes

Do STRAUB couplings need additional fixing points?
STRAUB-GRIP couplings need no additional fixing points.
One fixing point has to be installed per coupling when using STRAUB-FLEX or OPEN-FLEX-couplings.

Does the STRAUB principle also work on hard pipe surfaces?
Yes, the patented anchoring ring enables faultless anchoring to be achieved even with hard pipe material surfaces.

How well do STRAUB couplings attenuate pressure surges and noise in relation to a welded pipe connection?
Depending on the type of coupling used, attenuation values of 3 to 7-times better are achieved compared with welded or flanged connections.

Usable range for the various coupling sizes?
The spread of suitable pipe diameters for each coupling is given in the relevant data sheet. Problem-free installation of a coupler is guaranteed within this range. Under certain conditions, pipes having a diameter outside this range, can be connected. If in doubt, please contact a STRAUB solution manager.

What is the life expectancy for STRAUB sealing sleeves?
Under favourable conditions a life expectancy of over 25 years can be expected.

Can temporary raised temperatures be tolerated?
Yes, but repeated or extensive exceeding of the maximum operating temperature will result in a reduced life expectancy of the sealing sleeve.

Do STRAUB couplings also work under vacuum?
Yes, vacuums down to 50 mbar can be tolerated problem-free. An insert must be used when working under negative pressure conditions.

Can installation tolerances be added?
No, the given installation tolerances are restricted values for each particular case. The permissible value has to be reduced in the event of several cases occurring simultaneously. If in doubt, please contact a STRAUB solution manager.

Can STRAUB couplings withstand radial stress?
No. (Possible to a limited extent, whereby the coupling would be mis-aligned.)

What is the difference between a STRAUB-METAL-GRIP and a STRAUB-GRIP-L coupler?
Both couplings are axially restraint connectors for metal pipework. The STRAUB-METAL-GRIP is of a considerably stronger design. The STRAUB-GRIP-L is tough enough for about 75 % of all applications.

Is a STRAUB-OPEN-FLEX with its cut sealing sleeve leak-proof? How so?
Yes. The sealing sleeve is first manufactured as though for a FLEX coupling and then carefully cut through. This clean cut ensures edges with a 100% sealing performance.

In what intervals do the bolts have to be re-tightened?
The bolts never need to be re-tightened. STRAUB couplings are absolutely maintenance-free.

Do pipe ends need to be prepared?
No, simply remove dirt, rust or paint remains. Debur the pipe ends if necessary.

What is the life expectancy of a STRAUB coupling?
25 years or more is possible. There are couplings in use since 1974

What is the purpose of a strip insert?
Protection of the sealing sleeve under negative pressure conditions, to bridge large gaps between pipe ends, to prevent rubber swelling, to take up axial movements with angular displacement and to overcome axial displacement or external over-pressure.

How does the length changing concept of the STRAUB-FLEX/-OPEN-FLEX work?
The rim of the seal is flexing,  thereby taking up any axial movement in the pipe. Because of the special shape of the seal rim the coupling can compensate for a certain amount of axial change in pipe length without there being any friction between the surface of the pipe and the rubber seal. As a result, such movements can be absorbed an arbitrary number of times.

Why do we have a difference in nominal pressure between STRAUB-FLEX and STRAUB-OPEN-FLEX couplings?
Because of the divided casing (inherently weaker).

Are STRAUB couplings electrically conductive?
STRAUB-GRIP-L and STRAUB-METAL-GRIP couplings are electrically conductive. STRAUB-FLEX and STRAUB-OPEN-FLEX couplings can be made electrically conductive by use of a "current conductor".

For further queries or for additional information please contact:
Straub Werke AG, Straubstrasse 13, CH-7323 Wangs, Switzerland
Tel. +41 81-725 41 00, Fax +41 81-725 41 01, straub@straub.ch