abc® Aalco is a registered trademark of Aalco Metals Ltd
© Copyright: Aalco Metals Ltd, The Hersham Centre, Hersham Green, Hersham, Surrey KT12 4HP
All Data is indicative only and must not be seen as a substitute for the full specification from which it is drawn. In particular, the
mechanical property requirements vary widely with product form and product dimensions. For more complete details please refer to
the relevant specification – Specifications for Stainless Steel are listed on a separate Datasheet.
Stainless Steel Hygienics Guide
1. What are Hygienics?
♦ Stainless Steel Hygienics is the name given
to a range of tube and fittings used in
applications requiring a clean and sanitary
flow of liquids and where it is essential to
avoid contamination of the products being
carried.
♦ These applications cover the food
processing, beverage, biotech and
pharmaceutical industries including
breweries and dairies.
♦ The applications are low pressure with a
maximum of 150lbs.
♦ The products are available in grades 304L
and 316L.
♦ The size range is from ¾ inch to 4 inch
O/D.
♦ The tube and fittings are of welded
construction with the internal bead rolled
to flatten it and eliminate crevices, thus
preventing interruptions to the flow and
eliminating the risk of contamination or
bug traps as well as facilitate easy
cleaning.
♦ The tube and fittings are offered with a
choice of external finishes:
o Descaled
o Bright Annealed
o Dull Polished
o Semi-Bright or Bright Polished.
2. What is the manufacturing
standard?
♦ Hygienic tubes are manufactured to ASTM
A270, DIN 11850 and BS 4825 Part 1.
♦ Hygienic fittings are manufactured to
BS4825 Parts 2 to 5. (EN20286)
3. What markings will be on the tube
and fittings?
Tube and fittings with a bright annealed or
polished finish will be unmarked.
4. What is the size range?
Sizes to ASTM A270
O/D
in
Wall
Swg / mm
¾ 16 / 1.63
1 16 / 1.63
1½ 16 / 1.63
2 16 / 1.63
2½ 16 / 1.63
3 16 / 1.63
4 16 / 1.63
4 14 / 2.03
Sizes to DIN 11850
O/D
in
Wall
mm
1 1.5
1½ 1.5
2 1.5
2½ 1.5
3 1.5
4 2.0
For more information plus a complete
table of sizes and dimensions for all
hygienic fittings please visit the Down-
Loads page of the Aalco web site and
select the Tubular Products Databook.
(http://www.aalco.co.uk/literature/liter
ature.html#stainless)
abc® Aalco is a registered trademark of Aalco Metals Ltd
© Copyright: Aalco Metals Ltd, The Hersham Centre, Hersham Green, Hersham, Surrey KT12 4HP
All Data is indicative only and must not be seen as a substitute for the full specification from which it is drawn. In
particular, the mechanical property requirements vary widely with product form and product dimensions. For more
complete details please refer to the relevant specification – Specifications for Stainless Steel are listed on a separate
Datasheet.
5. What is the range of fittings?
Fitting Notes
Bends – 45 Degree, 90 Degree Bends & 180 Degree Returns
Pulled Tees
Pulled tees have a very short T-piece that is
unsuitable for automated machine orbital welding so
they can only be hand welded.
For orbital machine welding a full tee must be used.
Full Tees
Full tees can be welded by hand or on automated
orbital welding machines
Reducing Tees
abc® Aalco is a registered trademark of Aalco Metals Ltd
© Copyright: Aalco Metals Ltd, The Hersham Centre, Hersham Green, Hersham, Surrey KT12 4HP
All Data is indicative only and must not be seen as a substitute for the full specification from which it is drawn. In
particular, the mechanical property requirements vary widely with product form and product dimensions. For more
complete details please refer to the relevant specification – Specifications for Stainless Steel are listed on a separate
Datasheet.
Reducers – Concentric & Eccentric
Concentric
Eccentric
Seals – Material of Manufacture
The most common materials used for the
manufacture of seals are Nitrile Rubber and EPDM
Clamps
These comprise four parts – 2 Weld Ferrules, a
Gasket and a Clamp.
They are particularly used in systems carrying warm
semi-solids and viscous liquids such as chocolate
and tomato sauce, which must not cool in the line,
but tend to form regular blockages. Such systems
tend to need to be opened up quickly and often.
The clamp will have some form of closure device
such as a ‘Triclover’ clamp:
DIN Union
The DIN Union is rarely used in the UK.
The preferred unions are the RJT (Ring Joint Type)
and IDF (International Dairy Federation) types
abc® Aalco is a registered trademark of Aalco Metals Ltd
© Copyright: Aalco Metals Ltd, The Hersham Centre, Hersham Green, Hersham, Surrey KT12 4HP
All Data is indicative only and must not be seen as a substitute for the full specification from which it is drawn. In
particular, the mechanical property requirements vary widely with product form and product dimensions. For more
complete details please refer to the relevant specification – Specifications for Stainless Steel are listed on a separate
Datasheet.
RJT Union
The Ring Joint Type (RJT) Union comprises four
parts: - Nut - Liner - Seal - Male Part.
Primarily used where tubes are frequently
disassembled for cleaning.
The seal is of an ‘O Ring’ type and is made of Nitrile:
IDF Union
The International Dairy Federation (IDF) Union
comprises four parts: Nut - Liner - Seal - Male Part.
Here the liner is machined and the seal is a square
section. It has a thicker nut than the RJT and a
more substantial liner. It is machined rather than
pressed. It is considered easier to use.
The IDF has a smoother and cleaner flow line that is
free of crevices and bug traps. It is used where CIP
(Clean In Place) systems prevail, with the RJT only
tends to be used where very regular access is
needed.
The IDF seal has a square section and is more
substantial than the RJT. It is made of Nitrile or
EPDM:
abc® Aalco is a registered trademark of Aalco Metals Ltd
© Copyright: Aalco Metals Ltd, The Hersham Centre, Hersham Green, Hersham, Surrey KT12 4HP
All Data is indicative only and must not be seen as a substitute for the full specification from which it is drawn. In
particular, the mechanical property requirements vary widely with product form and product dimensions. For more
complete details please refer to the relevant specification – Specifications for Stainless Steel are listed on a separate
Datasheet.
This information is based on our present knowledge and is given in good faith. However, no liability
will be accepted by the Company is respect of any action taken by any third party in reliance thereon
As the products detailed may be used for a wide variety of purposes and as the Company has no control
over their use; the Company specifically excludes all conditions or warranties expressed or implied by
statute or otherwise as to dimensions, properties and/or fitness for any particular purpose. Any advice
given by the Company to any third party is given for that party’s assistance only and without liability on
the part of the Company.
Any contract between the Company and a customer will be subject to the Company’s Conditions of
Sale. The extent of the Company’s liabilities to any customer is clearly set out in those Conditions; a
copy of which is available on request.