Hermetic metal hose in a polymer sheath GERDA-MG (TU 4833-011-76960731-2008)
Connector for hermetic metal hose GERDA-SG (TU 1690-020-45416838-2008)

The hermetic metal hose GERDA-MG is designed to protect and safeguard cables, wires, flexible hoses, and other components from chemical and mechanical damage, moisture, and solar radiation. The GERDA-MG metal hose is suitable for open and concealed installation both indoors and outdoors, in ducts, tunnels, and trenches, and can be used in explosive zones of all classes. It is also permitted for use in transporting powdered and bulk materials.
GERDA-SG connectors ensure secure fastening of the metal hose to electrical equipment (junction boxes, pipes, device casings, cable trays, etc.), simultaneously creating a grounding circuit between them. At the same time, they provide a protection rating of IP67 against external influences (complete dust protection and water protection—allowing temporary immersion to a depth of up to 1 meter).

Metal hose construction

The metal hose is made from galvanized or stainless steel tape, over which a protective polymer sheath is applied (see Figure 1). The polymer sheath ensures complete hermetic sealing of the metal hose, protects it from harmful environmental effects, and significantly increases its tensile strength. The material of the polymer sheath is specified in Table 2.

A cotton thread is placed between the coils of the steel tape for sealing.
The metal hose is manufactured in the following versions:

- «P» (increased strength) — made from thicker metal tape and has higher tensile strength;
- «HL» (frost-resistant) — operating temperature from -60°C;
- «EHL» (for extreme cold climate) — operating temperature from -70°C;
- «T» (heat-resistant) — metal hose resistant to high temperatures, operating up to +200°C;
- «M» (oil and gasoline resistant) — sheath resistant to oil and gasoline exposure (tested according to GOST IEC 60811-2-1-2011);
- «X» — chemical resistance to acids and alkalis;
- «ZG» (rodent protection) — high-hardness sheath resistant to rodents, ants, and termites. Provides maximum abrasion resistance, which is essential for underground installation. Resistant to ultraviolet radiation and sunlight. Excellent chemical resistance to many acids and alkalis.

Connector construction

GERDA-SG connectors are made of nickel-plated brass. Based on the connection method to electrical equipment, the connectors are classified into the following types:
- «H» — with an external connection thread. Additionally, a nut can be ordered: flat (GP) or equipotential (GE) — see Table 5;
- «V» — with an internal connection thread;
- «Tr» — for pipes (see Figure 3). Thread cutting on the pipe is not required.
The external or internal connection thread of the connectors can be either metric or tapered inch NPT (see Table 5).
Figure 1. Construction of the hermetic metal hose GERDA-MG

Table 1. Dimensions of the GERDA-MG metal hose

Standard metal hose / high-strength «P» or stainless steel tape «N»

Nominal bore diameter (Du), mm	Inner diameter (d) not less than, mm	Outer diameter (D) not more than, mm	Minimum bending radius, mm	Breaking force, kgf	Weight per 100 m, kg	Coil length⁽¹⁾[max length], m
15	13.9	21.3	65 / 75	25 / 80	28 / 31	50 [100]
16	14.9	21.5	70 / 80	25 / 80	30 / 32	50 [100]
18	16.9	24.3	80 / 90	25 / 85	33 / 36	50 [100]
20	18.7	26.4	80 / 90	30 / 100	36 / 39	50 [90]
22	20.7	27.0	100 / 110	30 / 100	37 / 40	50 [80]
25	23.7	33.2	100 / 110	35 / 110	42 / 47	50 [70]
32	30.4	40.8	140 / 150	45 / 130	65 / 71	50 [50]
35	33.5	43.0	150 / 160	45 / 130	70 / 76	50 [50]
38	36.4	46.8	160 / 180	50 / 150	82 / 90	50 [50]
40	38.5	48.5	170 / 190	50 / 150	88 / 95	50 [50]
Note: ⁽¹⁾– Minimum order batch is 50 meters. The manufacturer may supply sections shorter than 50 meters, but no more than 20% of the batch. – GERDA-SG connectors are available for metal hoses highlighted in gray.

Table 2. Metal hose sheath designation and operating temperature depending on the material

Designation of the metal hose sheath	Description of the sheath material and properties	Operating temperature, °C
– (without designation)	PVC plasticate	-50°…+80°C
HL	PVC plasticate with increased frost resistance	-60°…+80°C
t	PVC plasticate with increased heat resistance	-50°…+105°C
ng	PVC plasticate with reduced flammability	-50°…+80°C
ng-HL	PVC plasticate with reduced flammability and increased frost resistance. The metal hose with NG-HL sheath is very flexible	-60°…+80°C
ng-LS	PVC plasticate with low smoke and gas emission	-50°…+80°C
ng-LS-HL	PVC plasticate with low smoke and gas emission, increased frost resistance	-60°…+80°C
ng-LS-EHL	PVC plasticate with low smoke and gas emission, for extremely cold climates	-70°…+70°C
ng-LS-EHL-M	PVC plasticate with low smoke and gas emission, for extremely cold climates, resistant to oils and gasoline	-70°…+70°C
ng-HF	Halogen-free polymer composition	-50°…+50°C
ng-HF-M	Halogen-free polymer composition, resistant to oils and gasoline	-50°…+50°C
ng-HF-HL	Halogen-free polymer composition with increased frost resistance	-60°…+50°C
ng-HF-HL-M	Halogen-free polymer composition with increased frost resistance, resistant to oils and gasoline	-60°…+50°C
ng-HF-EHL	Halogen-free polymer composition with increased frost resistance	-70°…+80°C
Tng	Flame-retardant thermoplastic elastomer, increased abrasion resistance	-60°…+125°C
Tng-M	Flame-retardant thermoplastic elastomer, resistant to oils and gasoline, increased abrasion resistance	-60°…+125°C
Tng-T	Heat-resistant flame-retardant thermoplastic elastomer, increased abrasion resistance; compared to “TNG,” the sheath is less flexible	-50°…+200°C
ng-LSLTx	PVC plasticate with low smoke and gas emission, low toxicity of combustion products	-50°…+80°C
ng-HFLTx	Halogen-free polymer composition, low toxicity of combustion products	-50°…+50°C
ng-HF-ZG	High-hardness polymer composition, halogen-free. Resistant to rodents, ants, and termites. Increased chemical resistance. Maximum resistance to abrasion and UV	-50°…+80°C
H	Polymer composition with increased chemical resistance to acids and alkalis	-50°…+80°C
Note: All metal hoses are resistant to solar radiation (UV). The most UV-resistant are black-colored metal hoses, as well as those with sheaths made of «HF» (halogen-free composition), «T» (thermoplastic elastomer), and «ZG» (rodent-resistant).

Figure 2. Structure of the GERDA-SG connector with external thread «N». The connector with internal thread «B» differs in the threading of the base (5).
Installation procedure for the connector (see Figure 2):
- Place the connector nut (2) and the polymer sealing ring (3) onto the hermetic metal hose (1);
- Screw the grounding sleeve (4) into the metal hose;
- Screw the connector base (5) into the housing of the electrical equipment;
- Hand-tighten the connector nut (2) onto the connector base (5), then tighten with a wrench by 1-2 turns. The tightening torque should not exceed 15 N∙m.

Connector for pipe GERDA-SG-Tr

The GERDA-SG-Tr connector allows easy attachment of the GERDA-MG hermetic metal hose to a pipe (see Figure 3). No threading is required on the pipe. The connector is securely fastened to the pipe thanks to the collet ring (8). A hermetic seal with the pipe is ensured by the elastomer sealing ring (6). The connector dimensions and pipe diameters are specified in Table 4.

Figure 3. GERDA-SG-Tr connector for a pipe. No threading on the pipe is required.
a) disassembled
b) assembled

Designation for ordering the GERDA-MG metal hose
TU 4833-011-76960731-2008

Material of the metal hose strip
–	galvanized steel
P	high-strength galvanized steel
N	stainless steel

Protective sheath color (default black)
–	black
C	blue
Zh	yellow or orange
B	white or gray
Z	green
K	red or pink
Kch	brown
Other colors – on request

GERDA-MG
–

16

–

P

–

ng-HL

–

C

Product type
Hermetic metal hose in a polymer sheath (IP67)

Nominal bore diameter Du, mm
15
16
18
20
22
25
32
35
38
40
For metal hoses marked in bold, GERDA-SG connectors are manufactured

Polymer sheath material (see Table 2)
–
HL
t
ng
ng-HL
ng-LS
ng-LS-HL
ng-LS-EHL
ng-LS-EHL-M
ng-HF
ng-HF-M
ng-HF-HL
ng-HF-HL-M
NG-HF-EHL
Tng
Tng-M
Tng-T
ng-LSLTx
ng-HFLTx
ng-HF-ZG
X

Example designation for ordering	Metal hose description
GERDA-MG-16-P-ng-HL-S TU 4833-011-76960731-2008	Sealed metal hose made of high-strength galvanized steel, Du=16mm, in a blue PVC sheath with low flammability and increased frost resistance. Operating temperature: −60°…+80°C, installation at temperatures down to −25°C.
GERDA-MG-22-ng-HF-ZG TU 4833-011-76960731-2008	Sealed metal hose made of standard-strength galvanized steel, Du=22mm, in a sheath made of a high-hardness polymer composition that does not contain halogens. The sheath is resistant to rodents, ants, and termites, with increased chemical resistance, maximum abrasion resistance, and UV resistance. Operating temperature: -50°…+70°C, installation at temperatures down to -15°C.

Table 3. Preferred application areas of GERDA-MG metal hoses considering their design type

Fire Safety Designation	Preferred Application Area of GERDA-MG Metal Hose
— (no designation), HL, t, X	For single installation in structures and industrial premises. Group installation is recommended only in outdoor electrical installations and industrial premises where personnel presence is only periodic.
ng, ng-HL, Tng, Tng-M, Tng-T	For group and single installation in open structures, trestles, galleries, and industrial premises.
ng-LS, ng-LS-HL, ng-LS-EHL, ng-LS-EHL-M	For installation in indoor electrical installations, as well as in buildings, structures, and enclosed cable facilities.
ng-HF, ng-HF-M, ng-HF-HL, ng-HF-HL-M, ng-HF-EHL, ng-HF-ZG	For installation in indoor electrical installations, as well as in buildings and structures with high human occupancy, including multifunctional high-rise buildings and building complexes.
ng-LSLTx, ng-HFLTx	For installation in buildings of preschool and educational institutions, specialized homes for the elderly and disabled, hospitals, and dormitory buildings of educational and childcare institutions.

Conditional designation when ordering the GERDA-SG connector
TU1690-020-45416838-2008

Connection to equipment
N	external thread
B	internal thread
Tr	collet (for pipe)

GERDA-SG
–

16

–

H

–

M20 x 1.5

Product type

Hermetic metal hose connector (IP67)

Nominal bore diameter of the metal hose Du, mm

16

22

25

35

40

Connectors are not manufactured for metal hoses with Du = 15, 18, 20, 32, 38 mm!

Type and size of connection thread (see Table 5)
–	no thread in the collet connection “Tr”
M	metric (with a 1.5 pitch)
K	tapered inch NPT (Type K according to GOST 6111-52)

Connector

Example designation when ordering	Connector description
GERDA-SG-16-H-M20x1.5 TU1690-020-45416838-2008	Hermetic metal hose connector Du=16mm (GERDA-MG-16), with external thread M20x1.5
GERDA-SG-22-Tr TU1690-020-45416838-2008	Hermetic metal hose connector Du=22mm (GERDA-MG-22) for connection to a pipe with an outer diameter of 24.5…28.0 mm. No threading on the pipe is required for connection

Table 4. Permissible outer pipe diameter for the "Tr" connector

Connector designation for pipe	Permissible outer pipe diameter D_н, mm
GERDA-SG-16-Tr	19.5…22.0
GERDA-SG-22-Tr	24.5…28.0
GERDA-SG-25-Tr	31.4…34.2
GERDA-SG-35-Tr	39.5…42.9
GERDA-SG-40-Tr	47.9…51.5

Designation for ordering an additional nut
TU1690-020-45416838-2008

Nut type for hermetic metal conduit connector (see Table 5)
GP		Flat nut
GE		Equipotential nut (only for metric thread M)

GP

–

M20 x 1.5

Connector thread type and size (see Table 5)
M	Metric (pitch 1.5)
K	Conical inch NPT (type K as per GOST 6111-52)

GE – ensures a reliable electrical connection between the connector and the electrical equipment housing; when tightened, the sharp teeth of the nut cut through the paint on the housing and make direct contact with the metal

Example designation when ordering	Nut description
GP-K1/2″ TU1690-020-45416838-2008	Flat nut for the hermetic metal hose connector GERDA-SG-16-N-K1/2″
GE-M25x1.5 TU1690-020-45416838-2008	Equipotential nut for the hermetic metal hose connector GERDA-SG-22-N-M25x1.5

Table 5

For hermetic metal hose

Order code for GERDA-SG connector
N — external thread
V — internal thread
Tr — for pipe
M — metric⁽¹⁾ thread
K — tapered inch NPT⁽²⁾

Dimensions of GERDA-SG connector⁽³⁾, mm

Types of connectors

Flat nut GP

Equipotential nut GE

Order code for GP nut

Size⁽³⁾, mm

Order code for GE nut

Size⁽³⁾, mm

Inner hole diameter, mm

A

B

Wrench C

Wrench E

Wrench D

A

Wrench B

A

Wrench B

GERDA-MG-16

GERDA-SG-16-N-M20x1.5

13.9

37

13

29

27

–

GP-M20x1.5

3

24

GE-M20x1.5

3.7

24

GERDA-SG-16-V-M20x1.5

–

GERDA-SG-16-N-K1/2″

GP-K1/2″

4

27

–

GERDA-SG-16-V-K1/2″

–

GERDA-SG-16-Tr⁽⁴⁾

58

–

30

36

–

GERDA-MG-22

GERDA-SG-22-N-M25x1.5

18.5

40

15

35

33

–

GP-M25x1.5

3.5

30

GE-M25x1.5

4.5

30

GERDA-SG-22-V-M25x1.5

–

GERDA-SG-22-N-K3/4″

GP-K3/4″

4

32

–

GERDA-SG-22-V-K3/4″

–

GERDA-SG-22-Tr⁽⁴⁾

60

–

36

41

46

–

GERDA-MG-25

GERDA-SG-25-N-M32x1.5

23.8

46

15

45

43

–

GP-M32x1.5

4

41

GE-M32x1.5

5

41

GERDA-SG-25-V-M32x1.5

–

GERDA-SG-25-N-K1″

GP-K1″

7

36

–

GERDA-SG-25-V-K1″

–

GERDA-SG-25-Tr⁽⁴⁾

66

–

46

50

–

GERDA-MG-35

GERDA-SG-35-N-M40x1.5

31.8

52

16

54

52

–

GP-M40x1.5

5

46

GE-M40x1.5

6

50

GERDA-SG-35-V-M40x1.5

–

GERDA-SG-35-N-K1.1/4″

GP-K1.1/4″

7

46

–

GERDA-SG-35-V-K1.1/4″

–

GERDA-SG-35-Tr⁽⁴⁾

72

–

55

60

–

GERDA-MG-40

GERDA-SG-40-N-M50x1.5

36.8

56

18

63

60

–

GP-M50x1.5

5

55

GE-M50x1.5

6.2

60

GERDA-SG-40-V-M50x1.5

–

GERDA-SG-40-N-K1.1/2″

GP-K1.1/2″

7

55

–

GERDA-SG-40-V-K1.1/2″

–

GERDA-SG-40-Tr⁽⁴⁾

74

–

65

70

–

¹ – Metric thread M according to GOST 24705-2004 (ISO 724:2003) with a pitch of 1.5.
² – NPT thread corresponds to the Russian standard thread K (GOST 6111-52, tapered inch with a profile angle of 60 degrees).
³ – Provided for reference, the manufacturer may change dimensions without prior notice.
⁴ – The allowable pipe diameter for the pipe connector is specified in Table 4.

Hermetic metal hose in a polymer sheath, with connectors