RECITALS
Whereas on 13 June 1994 Official Mexican Standard NOM-004-STPS-1993, on protection systems and safety devices on machinery, equipment and accessories in workplaces, was published in the Official Gazette of the Federation; Whereas this Ministry, on the basis of the first paragraph of the fourth transitory article of the Federal Regulation on Occupational Safety, Health and Working Environment, published in the Official Gazette of the Federation on 21 January 1997, has considered it necessary to make various amendments to that Official Mexican Standard, the purpose of which is to bring it into line with the provisions laid down in that regulatory instrument; Whereas on 26 May 1998, in compliance with article 46, paragraph I, of the Federal Law on Metrology and Standardisation, the Ministry of Labour and Social Welfare submitted to the National Advisory Committee for Standardisation on Occupational Safety, Health and Working Environment the preliminary draft Amendment to this Official Mexican Standard, and on that same date that Committee found it to be correct and agreed that it should be published in the Official Gazette of the Federation; Whereas, so as to comply with the guidelines contained in the agreement on the deregulation of business activity, published in the Official Gazette of the Federation on 24 November 1995, the amendments proposed to this Standard were submitted by the Ministry of Trade and Industrial Development to the Economic Deregulation Council for its opinion, and on the basis of that opinion the appropriate adjustments were made, whereupon that Ministry issued a favourable ruling on the amendments contained in this Standard; Whereas on 9 December 1998, in compliance with the Committee's Agreement and with article 47, paragraph I, of the Federal Law on Metrology and Standardisation, the Draft Amendment to this Official Mexican Standard was published in the Official Gazette of the Federation so that, within the 60 calendar days following that publication, interested parties could submit their comments to the National Advisory Committee for Standardisation on Occupational Safety, Health and Working Environment; Whereas, no comments having been received on this Draft Amendment to the Official Mexican Standard, and the chapter on Verification Units having been added in compliance with paragraph V of article 28 of the Regulation to the Federal Law on Metrology and Standardisation, the National Advisory Committee for Standardisation on Occupational Safety, Health and Working Environment granted its approval, and the following is hereby issued: OFFICIAL MEXICAN STANDARD NOM-004-STPS-1999, PROTECTION SYSTEMS AND SAFETY DEVICES ON MACHINERY AND EQUIPMENT USED IN WORKPLACES
CONTENTS
1. Purpose
To establish the safety conditions and the protection systems and devices to prevent and protect workers against the occupational risks generated by the operation and maintenance of machinery and equipment.
2. Scope
This Standard is in force throughout the national territory and applies in all workplaces which, by the nature of their processes, use machinery and equipment.
3. References
For the correct interpretation of this Standard, the following Official Mexican Standards and Mexican standards in force shall be consulted: NOM-001-STPS-1993, on safety and health conditions in the buildings, premises, installations and areas of workplaces. NOM-005-STPS-1998, on safety and health conditions in workplaces for the handling, transport and storage of hazardous chemical substances. NOM-017-STPS-1993, on personal protective equipment for workers in workplaces. NOM-022-STPS-1993, on safety conditions in workplaces where static electricity represents a risk.* NOM-026-STPS-1998, Safety and health colours and signs, and identification of hazards from fluids conveyed in pipework. NMX-CC-018-1996-IMNC, Guidelines for developing quality manuals.
Definitions
For the purposes of this Standard, the following definitions are laid down: a) labour authority; employment authority: the competent administrative units of the Ministry of Labour and Social Welfare that carry out inspection functions in matters of occupational safety and health, and the corresponding units of the federal states and of the Federal District acting in support of them. b) safety padlock: a lock that prevents any worker from starting up the machinery and equipment. c) stroke: the distance travelled by a component of a machine in a reciprocating movement. d) workplace: any place, whatever its name, in which production, marketing or service-provision activities are carried out, or in which persons work who are subject to an employment relationship. e) cycle: the reciprocating or rotary movement during which a component of a machine performs work. * For the correct interpretation of this Standard, NOM-022-STPS-1999, Static electricity in workplaces - safety conditions, shall be consulted once it is published in the Official Gazette of the Federation and enters into force. f) travel limit switch: a manual or automatic device that prevents the movement of the tool holder from the initial position to the point of operation. g) dielectric: a material that prevents electrical conductivity. h) sensing device: an element that keeps a mechanism in operation while no object interferes with its sensor and causes a stop. i) electrical discharge machine: a machine tool in which the metal of the workpiece to be machined is removed by the action of electrical discharges between the workpiece and an electrode immersed in an electrolytic or dielectric oil. j) two-hand control: the device that requires the operator to use both hands simultaneously to actuate it. k) preventive maintenance: the action of inspecting, testing and reconditioning machinery and equipment at regular intervals so as to prevent operating failures. l) corrective maintenance: the action of inspecting and repairing machinery and equipment that was working up to the moment at which it failed. m) machinery and equipment: the set of mechanisms and elements combined to receive a form of energy and transform it into a given function. n) protection by physical barriers: physical barriers designed and built to isolate the worker from a risk zone and thereby prevent harm to the worker's health. o) potential risk: the probability that machinery and equipment will cause injury to workers.
5. Obligations of the employer
para 5.1 Present to the labour authority, upon request, the documents that this Standard requires the employer to prepare.
para 5.2 Prepare a study analysing the potential risk generated by the machinery and equipment, which shall include an inventory of all hazardous factors and conditions affecting the health of the worker.
para 5.2.1 In preparing the potential risk study, the following shall be analysed:
a) the moving parts and the generation of heat and static electricity of the machinery and equipment;
b) the cutting surfaces, and the ejection and heating of raw material, by-product and finished product;
c) the handling and condition of hand tools.
para 5.2.2 For every risk identified, the following shall be determined:
a) the type of harm;
b) the severity of the harm;
c) the probability of occurrence.
para 5.3 On the basis of the potential risk study, the employer shall:
a) prepare the Specific Safety and Health Programme for the Operation and Maintenance of Machinery and Equipment, make it known to the workers and ensure that it is complied with;
b) have trained personnel and a first-aid manual defining the procedures for responding to emergencies. The non-mandatory guide of Mexican Official Standard NOM-005-STPS-1998 may be used as a reference;
c) mark the traffic and operating areas in accordance with NOM-001-STPS-1993 and NOM-026-STPS-1998;
d) provide workers with personal protective equipment in accordance with NOM-017-STPS-1993.
para 5.4 Train the workers in the safe operation of the machinery and equipment, and of the hand tools they use to carry out their work.
6. Obligations of the workers
para 6.1 Take part in the training provided by the employer.
para 6.2 Comply with the measures set out in the Specific Safety and Health Programme for the Operation and Maintenance of Machinery and Equipment.
para 6.3 Report to the employer when the protection systems and safety devices of the machinery and equipment are damaged, out of service or bypassed.
para 6.4 Use the personal protective equipment in accordance with the instructions for use and maintenance provided by the employer.
para 6.5 Keep hair short or tied back, and not wear chains, rings, bracelets, loose sleeves or other objects that could be a risk factor during operation.
para 6.6 Report to the employer any malfunction of the machinery and equipment that may involve a risk.
7. Specific Safety Programme for the Operation and Maintenance of Machinery and Equipment
para 7.1 Operation of the machinery and equipment. The programme shall contain procedures to ensure that:
a) the guards and safety devices are installed where required and are used during operation;
b) the work area is kept clean and tidy;
c) the machinery and equipment are adjusted so as to prevent a risk;
d) the connections of the machinery and equipment and their electrical contacts are protected and are not a risk factor;
e) the changing and use of hand tools and tooling is carried out safely;
f) operating activities are carried out safely;
g) the system for feeding in and removing raw material, by-product and finished product is not a risk factor.
para 7.2 Maintenance of the machinery and equipment. The programme shall contain:
para 7.2.1 The training that shall be given to the workers who carry out maintenance activities.
para 7.2.2 The frequency and the procedure for carrying out preventive and, where applicable, corrective maintenance, so as to ensure that all components of the machinery and equipment are in safe operating condition; at least the following conditions shall be met:
a) on completion of maintenance, the guards and devices shall be back in place and in working order;
b) where machinery or equipment is modified or rebuilt, the safety conditions shall be preserved;
c) energy isolation (lock-out/tag-out) shall be carried out before and during the maintenance of the machinery and equipment, and the following shall also be complied with:
1) it shall be carried out by the person in charge of maintenance;
2) the workers involved shall be notified in advance when energy isolation is carried out;
3) the switches, valves and points requiring immobilisation shall be identified;
4) the energy shall be isolated at panels, controls or equipment, so as to de-energise, deactivate or prevent the operation of the machinery and equipment;
5) warning tags shall be attached in accordance with Appendix A;
6) the safety padlocks shall be fitted;
7) it shall be confirmed that the isolation has been carried out;
8) the workers involved shall be notified when the isolation has been removed.
The worker who attached the warning tags shall be the one who removes them.
para 7.2.3 A record shall be kept of the preventive and corrective maintenance carried out on the machinery and equipment, stating the date on which it was performed; this record shall be retained for at least twelve months.
8. Guards and safety devices
para 8.1 Guards on machinery and equipment. Guards are elements that cover machinery and equipment so as to prevent access to the point of operation and to prevent a risk to the worker.
para 8.1.1 It shall be verified that the guards meet the following conditions:
a) provide full protection to the worker;
b) allow the adjustments needed at the point of operation;
c) allow the worker to move freely;
d) prevent unauthorised workers from gaining access to the danger zone;
e) not interfere with the operation of the machinery and equipment;
f) not be a risk factor in themselves;
g) allow the visibility needed to carry out the operation;
h) be marked where their function is not self-evident, in accordance with NOM-026-STPS-1998;
i) be integrated into the machinery and equipment where possible;
j) be fixed in place and strong enough to perform their function safely;
k) not obstruct the removal of waste material.
para 8.1.2 Protection shall be incorporated into the control actuator to prevent accidental operation.
para 8.1.3 In workplaces where the layout of the machinery and equipment makes it impossible to use guards to enclose mechanical power transmission components, the obstacle protection technique shall be used. Where guardrails are used, they shall meet the conditions laid down in NOM-001-STPS-1993.
para 8.2 Safety devices. These are elements that shall be installed to prevent a hazardous phase from developing as soon as the presence of a worker, or of part of the worker's body, is detected within the danger zone of the machinery and equipment.
para 8.2.1 The machinery and equipment shall be fitted with safety devices for emergency stopping that are easy to activate.
para 8.2.2 The machinery and equipment shall have safety devices ensuring that power failures do not create hazardous conditions.
para 8.2.3 It shall be ensured that the safety devices meet the following conditions:
a) be accessible to the operator;
b) where their function is not self-evident, the presence of a safety device shall be marked in accordance with NOM-026-STPS-1998;
c) provide full protection to the worker;
d) be integrated into the machinery and equipment;
e) allow for their maintenance, upkeep and general cleaning;
f) be protected against inadvertent operation;
g) the device shall ensure that a fault in the system does not prevent the device's own operation and, in turn, prevents the cycle from starting until the fault has been corrected;
h) where the worker has to feed materials into, or remove them from, the point of operation by hand and this presents a risk, a two-hand control device, an interlocked guard device or a presence-sensing device shall be used.
para 8.2.4 In the case of electrical discharge machines, in addition to the requirements of the preceding paragraph, the following shall apply:
a) a brake indicator and control system shall be provided;
b) any significant increase in the normal stopping time of electrical discharge machines with air clutches shall be prevented, and further operation shall be inhibited in the event of a failure of the operating mechanism.
para 8.2.5 On machinery and equipment fitted with a limit switch, the following shall be complied with:
a) the limit switch shall be protected against unintended operation;
b) the mechanically driven clutch shall be able to disengage on completion of a cycle;
c) operation shall only be capable of being restored at the worker's discretion.
9. Verification units
para 9.1 The employer may choose to engage an accredited and approved Verification Unit, as provided for in the Federal Law on Metrology and Standardisation, to verify or assess compliance with this Standard.
para 9.2 Verification units may certify compliance with this Standard by verifying sections 5.2, 5.3 and 5.4, as well as chapter 7 in its sections 7.1 and 7.2 and chapter 8; for that purpose they shall have procedures for carrying out the documentary review and for verifying the technical performance of the survey and assessment, in compliance with the Mexican Standard NMX-CC-018-1996-IMNC in force.
para 9.3 The Verification Unit shall present its results in accordance with the corresponding list in
Appendix B.
para 9.4 The opinion issued by the Verification Unit shall be valid for five years, unless the guards or devices are modified.
APPENDIX A. WARNING TAG
A.1 Warning tags are signs of rectangular geometric shape, used to warn that machinery and equipment have been deactivated; they prohibit activation, and prohibit the removal of the tags by workers not involved in the maintenance. The tags shall be placed where the machinery and equipment are started up, and secured so that they cannot easily be removed.
A.1.1 Warning tags shall be visible from at least one metre away. Table A1 sets out the characteristics that warning tags shall meet.
TABLE A1. CHARACTERISTICS OF WARNING TAGS
A.1.2 The dimensions of warning tags shall conform to those indicated in figure A1. The graphics in the document cannot be shown in the HTML format, so it shall be consulted using the image option.
APPENDIX B. MINIMUM CONTENT OF THE OPINIONS OF THE VERIFICATION UNITS
B.1 Details of the undertaking assessed: a) name, style or company name; b) address; 1) street; 2) number; 3) district; 4) city; 5) postcode; 6) borough or municipality; 7) state; c) name and signature of the legal representative.
B.2 Details of the Verification Unit: a) name, style or company name; b) registration number with the Ministry of Labour and Social Welfare; c) conclusion on the results of the verification carried out, in accordance with this Standard; d) name and signature of the legal representative; e) place and date of signature.
Table A1 · Characteristics of warning tags
| MESSAGE | TEXT COLOUR | BACKGROUND COLOUR | |
|---|---|---|---|
| INFORMATION | CAUTION | BLACK | YELLOW |
| SECONDARY INFORMATION | PROHIBITION | BLACK | WHITE |
| The machinery or equipment shall not be started up, nor shall the tag be removed from the place where it was fixed. |
| ADDITIONAL INFORMATION | Any text considered necessary to add | BLACK | WHITE |
10. Enforcement
Enforcement of compliance with this Standard is the responsibility of the Ministry of Labour and Social Welfare.
11. Bibliography
a) ANSI-B11. 6-1984, Safety Requirements for Construction, Care and Use. For Machine Tools- Lathes. United States of America. b) ANSI-B11.8-1983. American National Standard for Machine Tools Drillind, Milling and Machines Safety Requeriments for Construction, Care and Ude. United States of America. c) JIS B6-1983. Test Code for Preformance and Accuracy of Wire Electrical Discharge Machines. United States of America. d) Model Code of Safety Regulations for Industrial Establishments for the Guidance of Governments and Industry, Chapter II Premises of Industrial Establishments; Chapter IV Machinery Guarding; Chapter V Electrical Equipment R.110 Earthing; Chapter IX Handling and Transport of Materials. Geneva, 1950. International Labour Organization.
12. Correspondence with international standards
This Standard does not correspond to any international standard, as no such reference existed at the time of its drafting.
TRANSITORY PROVISIONS
FIRST.- This Official Mexican Standard shall enter into force sixty days after its publication in the Official Gazette of the Federation. SECOND.- During the period indicated in the preceding article, employers shall comply with Official Mexican Standard NOM-022-STPS-1993, on safety conditions in workplaces where static electricity represents a risk, or shall carry out the adaptations needed to observe the provisions of this Official Mexican Standard and, in the latter case, the labour authorities shall provide, at the request of the interested employers, advice and guidance for putting compliance into effect, without the employers becoming liable to penalties for non-compliance with the Standard in force. THIRD.- Upon the entry into force of this Standard, the following Official Mexican Standards are cancelled: NOM-107-STPS-1994, Technical prevention of accidents in machines and equipment operating in a fixed place - mechanical and thermal safety - terminology, published in the Official Gazette of the Federation on 12 January 1996; NOM-108-STPS-1994, Technical prevention of accidents in machines and equipment, design or adaptation of protection systems and devices, risks arising from mechanical movements, published in the Official Gazette of the Federation on 16 January 1996; NOM-109-STPS-1994, Technical prevention of accidents in machines operating in fixed places - Guards and safety devices, types and characteristics, published in the Official Gazette of the Federation on 16 January 1996; NOM-110-STPS-1994, Safety in machine tools for drilling, milling and boring, published in the Official Gazette of the Federation on 11 May 1995; NOM-111-STPS-1994, Safety in machine tools known as electrical discharge machines, published in the Official Gazette of the Federation on 22 January 1996; NOM-112-STPS-1994, Safety in machine tools known as rolling, forming and bending machines, published in the Official Gazette of the Federation on 11 May 1995. Effective Suffrage. No Re-election. Mexico, Federal District, on the sixth day of the month of May of nineteen ninety-nine.- The Minister of Labour and Social Welfare, Mariano Palacios Alcocer.- Signed. REFERENCE GUIDE GUARDS AND SAFETY DEVICES The content of this guide is a supplement for a better understanding of this Standard and is not mandatory; its aim is to show the different guards and devices for fitting to the machinery and equipment that require them. Guards are elements that cover machinery and equipment to prevent access to the point of operation and to prevent a risk to the worker. In their installation and operation it is recommended that ergonomic aspects be considered, covering: the posture of the worker, the static and dynamic work of the activity, and the location of the control elements. A description of the most common guards follows: The graphics in the document cannot be shown in the HTML format, so it shall be consulted using the image option.