Brass fittings and threaded accessories for immersion heaters

1. Immersion heaters brass fittings



1: Assembly screw, M4 or M5 5: Grounding stud M4 or M5 9: Anti-creep groove 13: Metric or BSPP thread 17: Enclosure
2: Machined flat surface 6: Rotation ring 10: Fitting 14: Large chamfer
3: Grounding nuts 7: Dented washer 11: Machined flat surface 15: Centering embossing
4: Dented washer and saddle 8: Silicone waterproof gasket 12: Unlosable gasket groove 16: Unlosable gasket


– Fittings for incorporation by immersion heater manufacturers
– Fit the full range of immersion heater enclosures
– Compact size and short length result in reduced weight ( save + / -30% compared to double thread fittings)
– The fitting thread lengths allow throw wall mounting with fiber gasket and nut on wall of 6 mm thickness (9 mm for 2” and above) or on threaded socket with gasket
– Allows a 360° rotation of enclosure when mounted with their rotation ring

Range: complete, covering all usual diameters from 1 1/4” to M77x2

– Threads machined after forging according to:
– ISO965-1 and 2 for metric threads
– ISO228-1 (Pipe threads without sealing in the thread) for thread called “Gas Thread”, also known as BSPP.
– Thread clearance for captive gasket
– Large chamfer facilitating correct assembly
– Large machined gasket seat

Manufacturing process:
Hot forged, followed by lathe machining.
This technique allows a limited machining and reduces material losses, significantly improves the mechanical properties and provides a good surface without porosity.

Assembly on enclosures:
– Through a hole in the enclosure. The enclosure is sandwiched between the fitting and a stamped inner ring. Bumps in the ring provide self-centering.
This stamped ring costs only 10% of the conventional threaded inner rings.
On 2”, M77x2 and 2 ½” diameters, the drilling diameter is identical to models using a threaded ring. Therefore, no special drill diameter is needed.

Gasket between fitting and enclosure:
– 4 x 2 mm section, 50 Shore silicone gasket with anti-creep rib, absorbs flatness differences, and remains in place during tightening.
– Guaranteed IP65 ingress protection up to 200 ° C between fitting and enclosure, provided it has a flat bottom without asperities.

Grounding (earthing):
The grounding terminal does not impinge on the surface used for the heating elements brazing, allowing the larger diameter heating elements tubes and larger bending radius, and room for a center pocket tube. See general design of the grounding hereunder.

Fitting gasket:
Three models of captive gaskets can cover all applications
– Non-asbestos fiber gasket, thickness 2 mm
– NBR O-ring, dia. 4 mm
– Flat PTFE gasket, thickness 2 mm

Inner stamped ring:
– The outside diameter less than or equal to the threaded rings allows to replace them without footprint problem.
– Its large inner diameter does not reduce the passage for heating elements
– The clamping with 3 BTR screws at 120° ensures a good pressure distribution and an excellent mechanical strength. These screw positions increase the clearances between the screw heads and live parts of the heating elements (If respecting the most favorable angle when drilling heating element holes)
– The recessed hexagonal hole screw heads allow easy and stable entry of hex wrench when adjusting angular position (M4 screw up to 2 “above M5)
– Ring made of stainless steel for better durability
– Unalterable stamped earthing logo

Brazed joint:
Wall thickness of 4 mm to ensure sufficient length of solder to minimize capillary leakage and provide good vibration resistance

Fitting clamping: 8mm wide hex part for easy passage of wrench

Pressure resistance: 2 MPa (Fitting undrilled and without heating elements). The minimum wall thickness meets the Schedule 10S specs.

Brazing and hard soldering ability:
Common brass alloys used for hot forging have a 2 to 3% lead content. This high percentage of lead weakens the brass when heated to high temperatures (as
it happens in “Hard soldering” and brazing) and also makes them unsuitable for oxy-acetylene welding.
The alloy used for these connections has a low lead content, which improves its brazing ability.

– Hole drilling and chamfering for heaters according to customer drawing (MOQ apply)
– Customizing or customer references marking (MOQ apply)


2. Brass raw material

Nearest equivalences Specific
HB hardness Tensile strength Rp0,2 (Mpa) Extension %
H59Pb1 CuZn39-Pb2 (Afnor-51-104)
CuZn37-Pb0.5, (Din 17760)
C37000 (ASTM)
CW617N (EN12165)
8.4 80-120 350 15-30%



Cu Fe Pb Ni Zn Impurities total
57~60% ≤ 0.5% 0.08-1.9% ≤1 % surplus ≤1%


2.1 Brass Rohs compliance

According to the Directive 2011/65/ dated June 8, 2011 (Rohs), copper alloys are allowed to have a maximum of 4% by weight of lead as an alloying element.
(Provisions of Article 4 and paragraph 1 of Annex II, limit value set by 6c of Annex III)

2.2 Earthing (grounding) provisions, Stainless steel and brass models

Earthing (Grounding) continuity. EN60335-1 requirements)

The design of the grounding connections was scheduled to meet all the points of this standard, and to ensure a grounding line, including in boxes with plastic. It complies in particular with the following specifications (extracted from the standard) and our solutions

27.1 Accessible metal parts of class I appliances that may become live in the event of an insulation fault, shall be permanently and reliably connected to
an earthing terminal within the appliance
Solution: fittings have a built-in earth terminal

27.2 The clamping means of earthing terminals shall be adequately secured against accidental loosening.
It shall not be possible to loosen the conductors without the aid of a tool.
Solution: earthing is made by nuts needing a wrench to screw and unscrew, and have dented washers

27.4 All parts of the earthing terminal intended for the connection of external conductors shall be such that there is no risk of corrosion resulting from contact between these parts and the copper of the earthing conductor or any other metal in contact with these parts.
Solution: The earthing terminal is made of nickel-plated brass or stainless steel that does not corrode with brass fitting and stainless steel

28.1 Earth connections which failures may provide a lack of earthing continuity shall withstand the mechanical stresses occurring in normal use.
Screws used for connections providing earthing continuity shall screw into metal.
Solution: The earth terminals withstand more than one and a half times the nominal torque required by the standards and are screwed into a threads made of brass or steel fittings

28.2 Connections providing earthing continuity shall be constructed so that contact pressure is not transmitted through insulating material that is liable to shrink or to distort
– Thread-cutting (self-tapping) screws shall not be used if they are likely to be operated by the user or installer.
– At least two screws must be used for each connection providing earthing continuity unless the screw forms a thread having a length of at least half the diameter of the screw
– The earth terminals are provided that even if they are used with a plastic housing, tightening the earth connection has no plastic or elastomeric gasket
– No self-tapping screw used for earthing
– When the earthing is made by a screw in a thread, the length thereof is always greater than the value given by the standard

28.4 Screws and nuts that make a mechanical connection between different parts of the appliance shall be secured against loosening if they also make connections providing earthing continuity.
– Sealing compound that softens on heating provides satisfactory security only for screw connections not subject to torsion in normal use.
Solution: The ground terminals are blocked by dented lock washers. No thread sealing compound used