Stainless steel hygienic couplings
Stainless steel hygienic couplings – general information
Hygienic couplings
Hygienic couplings are designed for the food, cosmetics, pharmaceutical and chemical industries as well as for biotechnology. The couplings must meet the precise demands of hygiene set for the particular application, related to the particular material, cleaning and sterilisation methods which do not require the installation to be dismantled (CIP – Cleaning in Process, SIP- Sterilization in Process). The hygienic installations and couplings are usually made of AISI304 or AISI316 stainless steel. The coupling must be designed so as not to have any crevices, dead spaces, corners and rough surfaces – not cleanable, where product particles may accumulate causing growth of microorganisms. The roughness of internal surface must not exceed Ra = 0.8 μm and Ra = 0.4 μm where the requirements are higher. Welds must fulfil separate, high requirements. The seals made of elastomer or plastic materials should be compliant with relevant hygiene standards.
DIN11851 stainless steel hygienic couplings
The threaded couplings according to DIN11851 standard with Rd (rounded) thread are extensively used in dairies, in the food and chemical industries. The seal with D-shaped cross section is made of either EPDM, silicone, NBR or Viton. In order to ensure higher level of hygiene the seal with a lip is used which fills the crevice between the connected halves of the coupling. Normally, DIN11851 couplings are in 316 steel (nut is in 304 steel). Maximum allowable working pressure (for DIN 11851 coupling alone) is 40 bar (DN10-DN40), 25 bar (DN50-DN100) and 16 bar (DN125-DN150). Sizes range from DN10 ÷ DN150. The product range includes male couplings (threaded), female couplings (conical), round slotted nuts, intended to be welded directly to an installation or assembled to rubber and plastic hoses with clamps, clips or crimped with ferrules.
SMS stainless steel hygienic couplings
The threaded couplings according to SMS Swedish standard with Rd (rounded) thread are commonly used in the dairy and food industries. The flat sealing face of the coupling helps to disassemble the sections of the installation easily. The square cross section seal is made of either PTFE, Viton, EPDM or NBR. Made of 316 steel (nut is in 304 steel as standard). Maximum allowable working pressure (for the coupling alone) is 15 bar. Sizes range from DN25 ÷ DN100. The product range includes male couplings (threaded), female couplings (flat), round slotted nuts, intended to be welded directly to an installation or assembled to rubber and plastic hoses with clamps, clips or crimped with ferrules.
IDF stainless steel hygienic couplings
IDF coupling – threaded coupling with trapezoidal thread (International Dairy Federation, BS 4825-4 and ISO 2853 standards) is used in the dairy industry and food processing industry. A rubber seal with a T-shaped cross section perfectly fills up the surface of connection to obtain a crevice free design with good self-cleaning properties and thus a relatively high level of hygiene. Made of 316 steel (nut is in 304 steel as standard). Maximum allowable working pressure (for the coupling alone according to BS 4825-4) is 16 bar.
RJT stainless steel hygienic couplings
RJT couplings (Ring Joint Type, BS 4825-5 standard) are threaded couplings with Whitworth imperial thread, used especially in the British dairy industry and food industry. A thick o-ring (of NBR or EPDM rubber) seals the coupling. Can be easily dismantled. As the crevice is pretty large, the couplings are rather not suitable for cleaning without dismantling (CIP). Maximum allowable working pressure (for the coupling alone according to BS 4825-5) is 10 bar.
TRICLOVER stainless steel hygienic couplings
TRICLOVER couplings (also called: Triclamp) are of a symmetrical, flange coupling type. TRICLOVER couplings comprise two flanges („plates”) with grooves to accommodate a seal, and a clamp to compress and close both halves. The seal (silicone, PTFE, Viton, EPDM or NBR rubber) entirely fills up the crevice between two flanges and thus ensures unrestricted flow path and very high level of hygiene of the coupling. Therefore TRICLOVER couplings are used in many applications in the pharmaceutical, food, cosmetic and chemical industries, in biotechnology, for fluids and high viscosity media. TRICLOVER couplings are manufactured in compliance with such standards as: ISO 2852, DIN 32676, BS 4825-3, ASME-BPE and other, in which the basic dimensions of connections are usually the same. Basically, it specific to TRICLOVER couplings that the outer diameter of the flange and inner diameter at the outlet correspond to each other and to the inner diameter of the pipes in the installation. Made of 316 steel (clamps made of 304 steel as standard). TRICLOVER couplings usually feature the higher quality finish of the internal surface (roughness Ra up to 0,4 µm at the most). The working pressure of the coupling alone depends on the size of the coupling and type of the clamp applied (at least 16 bar up to 2” size, 10 bar – above 2”). The product range comprises couplings intended to be welded directly to an installation or assembled to rubber and plastic hoses with clamps or crimped with ferrules.