Bsi bs en 50078 1994 (1999)

www bzfxw com BRITISH STANDARD BS EN 50078 1994 Torches and guns for arc welding The European Standard EN 50078 1993 has the status of a British Standard UDC 621 791 75 03 620 1 614 8 BS EN 50078 1994[.]

BS EN 50078:1994

This British Standard, having

been prepared under the

direction of the Welding

Standards Policy Committee,

was published under the

authority of the Standards

Board and comes

into effect on

15 April 1994

© BSI 03-1999

The following BSI references

relate to the work on this

standard:

Committee reference WEE/6

Draft for comment 89 78623 DC

ISBN 0 580 23072 4

Cooperating organizations

The European Committee for Electrotechnical Standardization (CENELEC), under whose supervision this European Standard was prepared, comprises the national committees of the following countries:

Amendments issued since publication

EN 50078:1993 Torches and guns for arc welding published by the European

Committee for Electrotechnical Standardization (CENELEC)

EN 50078 was produced as a result of international discussion in which the UK took an active part

A British Standard does not purport to include all the necessary provisions of a contract Users of British Standards are responsible for their correct application

Compliance with a British Standard does not of itself confer immunity from legal obligations.

Torches and guns for arc welding

Torches pour le soudage à l’arc Brenner zum Lichtbogenschweißen

This European Standard was approved by CENELEC on 1993-12-08

CENELEC members are bound to comply with the CEN/CENELEC Internal

Regulations which stipulate the conditions for giving this European Standard

the status of a national standard without any alteration

Up-to-date lists and bibliographical references concerning such national

standards may be obtained on application to the Central Secretariat or to any

CENELEC member

This European Standard exists in three official versions (English, French,

German) A version in any other language made by translation under the

responsibility of a CENELEC member into its own language and notified to the

Central Secretariat has the same status as the official versions

CENELEC members are the national electrotechnical committees of Austria,

Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy,

Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and

United Kingdom

CENELEC

European Committee for Electrotechnical StandardizationComité Européen de Normalisation ElectrotechniqueEuropäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B-1050 Brussels

© 1993 Copyright reserved to CENELEC members

Ref No EN 50078:1993 E

This European Standard was prepared by

CENELEC Technical Committee TC 26A, Electric

arc welding

It was submitted to the CENELEC members for

formal vote in September 1992 and was approved by

CENELEC as EN 50078:1993 on 8 December 1993

The following dates were fixed:

For products which have complied with the relevant

national standard before 1994-06-01, as shown by

the manufacturer or by a certification body, this

previous standard may continue to apply for

production until 1999-06-01

Annexes designated “normative” are part of the

body of the standard Annexes designated

“informative” are given only for information In this

standard, Annex A and Annex C are informative

and Annex B is normative

4.5 non-consumable electrode (TIG, plasma) 5

— latest date of publication

EN 50078:1993

Page8.4 Determination of the ambient air

Annex A (informative) Additional

Annex B (normative) Position of the

welding torches for the heating test 15

Annex C (informative) Cooled copper block 16

Figure 1 — Device for testing the

Figure 2 — Device for the impact test 12

Figure B.1 — MIG/MAG and MOG torches 15

Figure C.1 — Example for a water-cooled

Table 2 — Degree of protection for manual

Table 3 — Degree of protection for

Table 4 — Test values for MIG welding of

Table 5 — Test values for MAG welding of

Table 6 — Test values for MAG welding

Table 7 — Test values for MOG welding

Table 8 — Test values for TIG welding 10

Table 9 — Test values for plasma welding 10

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This standard is applicable to torches and guns for

MIG/MAG, MOG, TIG and plasma welding

This standard is not applicable to electrode holders

for manual metal arc welding and to torches for

plasma cutting or submerged arc welding

This standard is not applicable to unprotected

torches used in automatic equipment, where

protection against direct contact is provided by

other means

This standard specifies safety and construction

requirements

2 Normative references

This European Standard incorporates by dated or

undated reference, provisions from other

publications These normative references are cited

at the appropriate places in the text and the

publications are listed hereafter For dated

references, subsequent amendments to or revisions

of any of these publications apply to this European

Standard only when incorporated in it by

amendment or revision For undated references the

latest edition of the publication referred to applies

EN 60529:1989, Degrees of protection provided by

enclosures (IP Code) (IEC 529:1989)

prEN 758, Classification of tubular cored electrodes

for metal arc welding with or without gas shield of

non alloy and fine grain steel

a unit that conveys all services necessary to the arc

for welding, cutting or allied processes (e.g current,

gas, coolant, electrode wire)

NOTE 1 In the case of a torch the handle is co-axial with the

body and the neck may be straight or curved.

In the case of a gun the handle is substantially perpendicular to

the body.

NOTE 2 In this standard the terms “torch” and “gun” are, for most purposes, interchangeable For convenience “torch” has been used in the following text.

4.2 body

the main component to which other components and the cable-hose assembly are connected

4.3 handle

the part designed to be held in the operator’s hand

4.4 nozzle

a hollow component, fixed at the front end of the torch for directing the shielding gas around the arc and over the weld pool

4.5 non-consumable electrode (TIG, plasma)

a metal electrode which does not provide filler metal

4.6 electrode wire (MIG, MAG, MOG)

consumable solid or flux cored wire that passes through the contact tip The arc is formed between the electrode and the workpiece

4.7 contact tip (MIG, MAG, MOG)

a replaceable metal component fixed at the front end

of the torch, through which the electrode wire passes and which conducts the welding current to the electrode wire

4.8 cable-hose assembly

a flexible assembly of cables and hoses and their connecting elements, that delivers all necessary supplies for operation of the torch

4.9 MIG/MAG torch

a torch using an electrode wire The arc and the weld pool are shielded by an inert (MIG) or active (MAG) gas

NOTE MIG and MAG are abbreviations for “metal inert gas”

and “metal active gas” respectively.

4.10 MOG torch

a torch using a flux cored wire The weld pool is shielded by the slag of the molten core The arc is shielded by gas produced during melting of the core

NOTE MOG is an abbreviation for “Metall ohne Gas” (metal without gas).

a) Range of the temperature of the ambient air:

a torch using a non-consumable electrode The weld

pool and the non-consumable electrode are shielded

by an inert gas

NOTE TIG is an abbreviation for “tungsten inert gas”.

4.12

plasma torch

a torch using a non-consumable electrode and

having a plasma tip producing a constricted plasma

arc

4.13

plasma welding torch

a plasma torch for welding

mechanically guided torch

a torch held and guided mechanically

4.16

air cooled torch

a torch cooled by the ambient air and, where

appropriate, by the shielding gas

4.17

liquid cooled torch

a torch cooled by a liquid

Torches shall be classified according to:

a) the process for which they are designed

(see 5.1);

b) the method by which they are guided (see 5.2);

c) the voltage class (see 5.3);

d) the type of cooling (see 5.4);

e) accessory equipment, e.g integrated wire drive systems and reel for the electrode wire

b) mechanically

5.3 Voltage class

The voltage classes are characterized by:

a) the maximum rated voltage with the letters:

— L (up to 113 V peak)or

— M (113 V peak up to 400 V peak)and

b) the rated striking and stabilizing voltage

5.4 Type of cooling

Torches can be cooled by:

a) air or cooling gas (see 4.16)

or

b) liquid (see 4.17).

All tests are type tests They shall be carried out on

the same initially new and completely assembled

torches, fitted with their cable-hose assemblies

The heating test according to 8.2 shall be carried out

at an ambient air temperature between 10 °C

and 40 °C

The accuracy of measuring instruments shall be:

The tests may be carried out in any convenient

sequence except that the temperature rise test shall

be followed immediately by the dielectric strength

tests

7 Protection against electric shock

7.1 Insulation resistance

The insulation resistance of a new torch shall, after

the humidity treatment, be not less than the

following values:

Compliance shall be checked by the following test:

a) Humidity treatment

A humidity cabinet is maintained at a

temperature t between 20 °C and 30 °C and a

relative humidity between 91 % and 95 %

The torch fitted with the cable-hose assembly

(liquid-cooled torches without cooling liquid) is

brought to a temperature between t and

t + 4 °C and is then placed for 48 h in the

humidity cabinet

b) Insulation resistance measurement

Immediately after the humidity treatment,

the torch and the cable-hose assembly are

wiped clean and tightly wrapped in a metal

foil covering the external surface of the

insulation

The insulation resistance is measured by

application of a d.c voltage of 500 V between

— the live part connections and the metal

foil and exposed conductive parts and

— the control switch and adjustment control

connections and the connections of the other

Table 1 — Dielectric test voltages

The test voltage shall be of an appropriate sine wave form with the peak value not exceeding 1,45 times the r.m.s value, having a frequency of 50 Hz

Compliance shall be checked by the following test:

For the test, the torches from the preceding temperature rise test are used, after ensuring that they are still functioning and have reverted to approximately ambient air temperature Insulated handles are tightly wrapped with metal foil

Liquid-cooled torches are tested without cooling liquid

The full value of the test voltages is applied for 2 s between:

a) the live part connections and a test electrode with which exposed conductive parts, the metal foil and insulated parts can be contacted;

b) the control switch and adjustable control connections and to a test electrode with which the other live part connections can be contacted

7.3 Protection against direct contact

According to EN 60529 the degree of protection shall correspond to the requirements given in Table 2 and Table 3

Table 2 — Degree of protection for manual

torches

a) electrical measuring instruments: class 0,5;

b) temperature measuring device: ± 2 K

EN 50078:1993

Table 3 — Degree of protection for

mechanically guided torches

Compliance shall be checked according to EN 60529.

7.3.1 Class M torches

Class M torches shall be so designed:

1) that an interlocking device de-energizes the

torch when parts are removed to expose the

electrode

or

2) that the parts that expose the electrode can be

removed and replaced only by use of a tool

The conditions for complying with this requirement

shall be given in the instructions for use [see 11 h)].

Compliance shall be checked by a functional test

together with the corresponding power source

8 Thermal rating

8.1 Temperature rise

The temperature rise at any point on the outer

surface of the part of the handle gripped by the

operator shall not exceed 30 K

The temperature rise at any point on the outer

surface of the cable-hose assembly shall not

exceed 40 K

After completion of the tests safety and operability

of the torch shall not be impaired

Compliance shall be checked by the heating test

according to 8.2.

8.2 Heating test

Each heating test shall be carried out on a torch,

fitted with the cable-hose assembly normally

supplied with it The length of the cable-hose

assembly shall be 3 m to 8 m

For the purpose of the test the cable-hose assembly

to the torch shall be connected directly to the

welding power source or the wire feed unit

The torches shall be loaded with the rated current

and the type of voltage as given in the instructions

for use [see 11 d)].

The load voltage shall be measured between the workpiece used in the test and the supply end of the welding cable of the cable-hose assembly

In the case of a.c current, steps shall be taken to ensure that the load current is symmetrical The measured value of the current shall be r.m.s, and the frequency 50 Hz or 60 Hz

In the case of d.c the mean value shall be taken and the electrode polarity shall be chosen in accordance

with 8.2.1 and 8.2.2.

A temperature measuring device shall be fixed at the hottest spot on the handle and the cable-hose assembly The temperature measuring device, handle and cable-hose assembly shall be protected from draughts and radiant heat

The torch clamping device used shall not significantly affect the test result e.g by heat loss

Torches shall be continuously Cooled with the flow and load loss conditions specified by the

manufacturer

The temperature reading shall be taken after half the loading period of the last cycle

8.2.1 MIG/MAG and MOG torch

A metal tube 400 mm to 500 mm in diameter and

at least 500 mm long is horizontally clamped into a rotating device The inside of the tube is cooled by means of water

The torch shall be positioned in a plane perpendicular to the tube axis in such a way, that the handle is on the cooler side and the electrode wire is 15° to the vertical (see Figure B.1)

The torch shall be moved parallel to the centre line

of the tube in order to form a weld bead

a) Test conditions for MIG welding of aluminium alloys

Class Nozzle orifice Other parts

Electrode wire: aluminium 3 % to 5 %

magnesiumType of voltage: d.c.; electrode polarity:

positiveShielding gas: argonTube material: AlMg 3 to AlMg 5Load voltage: U2 = 14 + 0,05 l2 (max 30 V)

EN 50078:1993

Table 4 — Test values for MIG welding of aluminium alloys

Table 5 — Test values for MAG welding of mild steel

Table 6 — Test values for MAG welding with flux-cored wire

b) Test conditions for MAG welding of mild steel

If additional values for the shielding gas CO2 are

specified in the instructions for use, an

additional test with this gas shall be carried out

according to the test conditions

c) Test conditions for MAG welding with flux

cored wire

d) Test conditions for MOG welding of mild steel

NOTE 1 Both types are classified in prEN 758 “Classification of tubular cored electrodes for metal arc welding with or without gas shield of non alloy and fine grain steels”.

NOTE 2 T XX YN1 is a wire designed with a fast freezing slag for all-positional welding.

101518222628

656055504540

101215182020

121212222222

1015182226

7060555045

1013152025

1212122525

253035

555040

151820

122525

a Recommended values.

Electrode wire: mild (low carbon) steel

Type of voltage: d.c.; electrode polarity:

positiveShielding gas: argon/CO2 mixed gas (80/20

nominal)Tube material: mild (low carbon) steel

Load voltage: U2 = 14 + 0,05 l2 (max 44 V)

Electrode wire: rutile typeType of voltage: d.c.; electrode polarity:

positiveShielding gas: argon/CO2 mixed gas

(80/20 nominal)Tube material: mild (low carbon) steelLoad voltage: U2 = 14 + 0,05 l2 (max 44 V)

Electrode wire: type 1: T XX YN1

type 2: T XX WN2