3. OSHA Outreach Safety Training General Industry Safety Standards Welding, Cutting, and Brazing أعمال اللحام والقطع Subpart Q & Subpart J 29 CFR 1910.251 – 29 CFR 1910.255 29 CFR 1926.350 – 29 CFR 1926.354

4. Introduction المقدمة يعتبر اللحام من أكثر الطرق الشائعة فى الصناعة لوصل المعادن يتم لحام ووصل المعادن بإستخدام الحرارة أو الضغط أو كلاهما عندما يتم لحام قطعتين من المعدن يتم صهرهما معا يمجرد إنتهاء عملية اللحام يكون اللحام أقوى من المعدن الأصلى

5. General Hazards General Hazards of welding include: Electrical Hazardsمخاطر الكهرباء Harmful Fumes الأدخنة الضارة Heat and Light الحرارة والضوء المبهر Radiation Fire and Explosions الحرائق والإنفجارات

6. Welding Health Hazards المخاطر الصحية للحام 1.Chemical Agentsالمواد الكيميائية : يمكن التعرض لإستنشاق أكاسيد الزنك فى حالة اللحام فى المعادن المطلية بالزنك. إستنشاق هذه الأبخرة يسبب ما يعرف بحمى أدخنة المعادن لها نفس أعراض الإنفلونزا. حمى ، غثيان ، جفاف فى الزور ، سعال تستمر هذه الأعراض لمدة 24 ساعة وتزول وهكذا

7. Cadmiumالكادميوم يستخدم الكادميوم كطلاء للمعادن لمنع الصدأ والتآكل التعرض لفترات بسيطة لتركيز عال من أبخرة الكادميوم يمكن أن يسبب حساسية شديدة للرئتين ، ضيق التنفس ، وفى بعض الحالات الوفاة. التعرض لتركيز منخفض لأبخرة الكادميوم لفترات طويلة قد يسبب emphysema وهو مرض يؤثر على مقدرة الرئتين لإمتصاص الأوكسيجين ومن الممكن أن يسبب فى تلف الكليتين

8. Skin irritation Eye irritation Inhalation 4f Acute health hazards

9. Ingestion Observable effects 4g

10. Chronic health hazards Carcinogen Kidney damage Respiratory damage 4h

11. Berylliumالبريليوم يستخدم كسبيكة مع سبائك النحاس التعرض اللحظى لتركيز عال من أبخرة البريليوم من الممكن أن يسبب الإلتهاب الرئوى التعرض لفترات طويلة لتركيز منخفض من أبخرة البريليوم من الممكن أن يسبب ضيق التنفس ، السعال المزمن ، نقص واضح فى الوزن

12. Fluoridesالفلورايد يستخدم لطلاء للإلكترود الذى يستخدم فى لحام الكهرباء وذلك لتكوين طبقة عازلة حول اللحام لمنع الأكسيجين من التفاعل مع المعدن وتلف اللحام يسبب حساسية للعين والأنف والزور التعرض المتكرر لتركيز عال من الفلورايد فى الجو لفترات طويلة من الممكن أن يسبب سوائل فى الرئة كذلك تلف العظام

13. Phosgeneالفوسيجين يتكون بسبب تحلل المذيبات العضوية التى تحتوى على الكلور بواسطة الأشعة فوق البنفسجية الناتجة من أعمال اللحام الكهربائى هذا الغاز يتفاعل مع السوائل بالرئة مكونا حمض الهيدروكلوريك الذى يدمر أنسجة الرئتين. لهذا الغرض تتطلب مواصفات الأوشا إبعاد المذيبات العضوية التى تحتوى على الكلور من قرب مكان اللحام بمسافة لا تقل عن 200 قدم (60 مترا)

14. 2- Physical Agentsالعناصر الفيزيائبة الأشعة فوق البنفسجية قد تسبب حروق شديدة للجلد وتتلف عدسة العين الأشعة تحت الحمراء تسبب فى تسخين سطح الجلد والأنسجة اسفل سطح الجلد الضوء المبهر لعمال اللحام قد يسبب زغللة النظر

15. Types of Weldingأنواع اللحام Gas Welding (oxy-acetylene gas)الغاز Arc Welding (SMAW – Shield Metal Arc Welding) – (MIG – Metal Inert Gas) – (TIG – Tungsten Inert Gas) Oxygen and Arc Cutting

16. 29 CFR 1910.252 General Requirements المتطلبات العامة إبعاد جميع المواد القابلة للإشتعال من قرب مكان اللحام بمسافة لا تقل عن 35 قدم (11 متر) فى حالة عدم إمكانية إبعاد المواد القابلة للإشتعال يتم تغطيتها بواسطة مادة غير قابلة للإشتعال. ضرورة وضع معدات مكافحة الحريق بالقرب من مكان اللحام

18. Continued ضرورة تكليف مراقب للحريق يتواجد بالقرب من مكان اللحام لمتابعة الشرر المتطاير ويكون مدربا على مكافحة الحرائق. بعد إنتهاء عملية اللحام يظل مراقب الحريق فى مكان اللحام مدة لا تقل عن ½ ساعة لملاحظة أية حرائق بطيئة قد تحدث نتيجة الشرر المتطاير.

21. Welding or Cutting Containers اللحام والقطع فى الحاويات والبراميل غير مسموح على الإطلاق اللحام والقطع فى الحاويات أو البراميل الفارغة ما لم يتم التأكد من خلوها تماما من الأبخرة القابلة للإشتعال

22. Protection of Personnel مهمات الوقاية الشخصية قفازات مقاومة للحرارة ملابس مقاومة للحرارة للحماية من الشرر والمعدن الساخن حذاء سلامة واقى للعين بفلتر حسب نوع اللحام

24. Filter Lens Shade Number Guide Welding OperationShade Number Shield Metal Arc Welding up to 4 mm electrode10 Shield Metal Arc Welding (4.8 to 6.4 mm) electrodes12 Shield Metal Arc Welding (6.4 mm) electrode14 Gas Metal Arc Welding (Nonferrous)11 Gas Metal Arc Welding (ferrous)12 Gas Tungsten Arc Welding12 Carbon Arc Welding10 – 14 Torch Soldering2 Torch Brazing3 or 4 Light cutting up to 25 mm3 or 4 Medium cutting 25 to 150 mm4 or 5 Heavy cutting over 150 mm5 or 6 Gas welding (light) up to 3.24 or 5 Gas welding (medium) 3.2 to 12.75 or 6 Gas welding (heavy) over 12.76 or 8

25. Health Protection and Ventilation التهوية والوقاية الصحية ضرورة توفير تهوية ميكانيكية لمكان اللحام ، ومعدل التهوية لا يقل عن 2000 قدم مكعب بالدقيقة لكل ماكينة لحام بالورشة. يتم توفير التهوية الميكانيكية فى المواقع التى يقل حجمها عن 10000 قدم مكعب (284 متر مكعب) وفى الغرف التى يقل إرتفاعها عن 16 قدم (5 متر). فى حالة وجود ورشة اللحام داخل ورشة أخرى يتم تركيب حاجز على أن يتم ترك 2 قدم فراغ من أسفل لسهولة التهوية.

26. Movable Hoods التهوية الموضعية تهوية موضعية متحركة يتم وضعها بالقرب من مكان اللحام لشفط الأبخرة الضارة قبل إستنشاقها بواسطة العامل. سرعة شفط الهواء فى هذه الشفاطات يجب ألا تقل عن 100 قدم بالدقيقة

29. 29 CFR 1910.253 Gas Welding and Cutting اللحام والقطع بالغاز An oxyacetylene welding outfits is basically made up of: cylinders of oxygen and acetylene, regulators, hoses, and a torch. Oxygen and Acetylene are stored in separate cylinders in a high pressure, which is controlled by the regulators. Hoses carry the gases from the cylinders to the torch. The green hose carries Oxygen. The red Hose carries Acetylene. The gases are mixed inside the torch. When burned they produce a very hot flame. The flame is regulated by interchangeable torch tips and by the torch valves.

31. Flash Back Arrestor on the acetylene and oxygen regulators

32. Gas Welding Flashback Arresters Flashback during oxy-fuel welding, cutting can cause serious injury. All gas welding or gas cutting equipment must be fitted with flash arresters. Flashback begins when the flame moves back from the welding tip and into the blowpipe, usually with a loud “bang” or a shrill hissing sound. Without a flashback arrester, the flame can travel extremely fast about 13 meter a second – up gas supply hoses to the regulator and possibly into the gas cylinders where it could cause an explosion.

33. Non-return Valves on the Torch

34. Oxyacetylene Welding Equipment

38. General Requirements Under no condition shall acetylene be generated or utilized at a pressure in excess of 15 psig. Using acetylene at a pressure in excess of 15 psig is a hazardous practice. Free gaseous acetylene is potentially unstable at pressure above 15 psig and could decompose with explosive violence.

39. Continued The decomposition characteristics of acetylene gas are avoided by keeping the gas in liquid solution and storing it in cylinders of unique construction. These cylinders contain porous calcium silicate filler (millions of microscopic pores) and a suitable solvent usually acetone. (has the ability to absorb over 400 times its own volume of acetylene at 70º F.

41. Continued When absorbed in this filler, the acetylene is divided into such small units that, should acetylene decomposition take place in one pore, the heat released is not enough to raise the temperature of the acetylene in the surrounding pores. Acetylene is usually supplied in cylinders which have the capacity of up to 300 cubic feet of dissolved gas under pressure of 250 psig at 70º F.

42. Continued Cylinders shall be kept far enough away from the actual welding or cutting operation so that sparks hot slag, or flame will not reach them. When this is impractical shields shall be provided. Cylinders containing Oxygen or Acetylene or any fuel gas shall not be taken into confined spaces. Oxygen cylinders and fittings shall be kept away from oil or grease, and shall not be handled with oily hands or gloves.

43. Continued Cracking: Before a regulator valve is connected, the valve shall be opened slightly and closed immediately. To clear the valve of dust or dirt. The person cracking the valve shall stand to one side of the outlet, not in front of it. Fuel gas cylinder valves shall be opened 1.5 turns and the wrench shall be left in position on the stem of the valve.

44. Safety Precautions

45. Check with a leak spray or soap solution that there is no leakage Adequate Ventilation Flashback Arrestor Remove flammable materials Workplace free from combustible materials Never expose the acetylene cylinder to strong heat A burning torch must not be hung on the regulator or expose the cylinder

46. Cylinders and Containers Compressed gas cylinders shall be legibly marked, for the purpose of identifying the gas content.(stenciling – stamping) Cylinders should be stored away from elevators, stairs, or gangways, or other areas where they might be knocked over or damaged by passing or falling objects.

49. Continued Where the cylinder is designed to accept a cap, shall always be in place, hand-tight, except when cylinders are in use or connected for use. The valve protection cap is designed to take the blow in case of cylinder falls. Acetylene cylinders shall be stored valve end up.

50. Oxygen Cylinders Oxygen cylinders in storage shall be separated from fuel-gas cylinders or combustible cylinders a minimum distance of 20 feet (6.1 m).

51. Oxygen Cylinders Or by a non- combustible barrier at least 5 feet (1.5m) high having a fire resistance rating of at least 1/2 hour.

52. ARC WELDING

53. 29 CFR 1910.254 Arc Welding and Cutting Most of the electric welder are typically AC/DC, 240 volt transformer types using electricity as the energy source. Arc welding uses the heat from an electric arc to melt and fuse base metals and welding-rod metal into one piece. The heat from the arc melts the flux coating on the rod.

55. ARC WELDING In arc welding, the intense heat needed to melt the metal is produced by an electric arc. The arc is formed between the actual work and an electrode wire.

57. Some Types of ARC Welding SMAW (Shielded Metal Arc Welding) GMAW (Gas Metal Arc Welding) GTAW (Gas Tungsten Arc Welding)

58. SMAW (Shielded Metal Arc Welding) Consists of an AC/DC arc burning between a consumable electrode and the workpiece to melt the joint area. The arc and the weld pool are shielded by gases and slags which result from the decomposition of the electrode coating.

59. Arc Shielding Metals at high temperatures tend to react chemically with elements in the air (oxygen – nitrogen) oxides and nitrides form which destroy the strength and toughness of the weld joint. Protective covering with protective shield of gas, vapor, or slag.

60. GMAW (Gas Metal Arc Welding) (MIG) Metal Inert Gas Means the use of an inert (i.e. non active) gas. The process consists of a DC arc burning between a thin bare metal wire electrode and the workpiece. The arc and weld area are enveloped in a proactive gas shield. The wire electrode is fed from a spool, through a welding torch which is connected to the positive terminal into the weld zone.

63. GTAW (Gas Tungsten Arc Welding) TIG (Tungsten Arc Welding) Consists of an AC/DC arc burning between a non- consumable electrode and the workpiece to melt the joint area. The area of the arc is enveloped in a protective gas shield which protects the weld pool and electrodes from contamination while allowing a stable arc to be maintained. The filler wire is added by hand, or in the mechanised process, by feed rollers attached to the torch. For high quality welding on stainless steels, aluminium.

64. Tungsten Inert Gas DC most normally used for TIG welding of stainless steels, mild and low alloy steels, copper. The electrode must be connected to the negative terminal, where one third of the heat is generated. Two thirds of the heat of the arc is generated at the positive pole. A tungsten electrode connected to the positive pole would overheat and melt causing contamination of the weld and cracks in the ceramic shroud. AC is used only for welding of aluminum, magnesium. Surface oxidation is removed automatically by the action of the arc each time the electrode becomes positive.

65. Safety Measure The tungsten electrodes contain small amounts of thorium (less than 4%) which readily burning in air forming thorium oxide. Thorium is a radioactive metal and poses an inhalation and ingestion hazard. Good insulation of all power cables. Secure welding return clamps and protection against arc radiation.

69. Installing the Arc Welder The frame or case of welder shall be properly grounded. A safety type disconnecting switch shall be located near the machine. The welder shall be protected by properly sized fuse or circuit breaker on an independent circuit.

70. Continue A ground return cable shall have a safe current carrying capacity equal to or exceeding the specified output capacity of the arc welding or cutting unit which it services. Pipelines containing gases or flammable liquids or conduits containing electrical circuits, shall not be used as ground return.

71. Continue All arc welding and cutting cables shall be of the completely insulated, flexible types, capable of handling the maximum current requirements of the work in progress. Only cable free from repair or splices for a minimum distance of 10 feet from the cable end to which the electrode holder is connected shall be used.

72. Safety Measures Since the inert-gas metal-arc welding process involves the production of ultra-violet radiation on intensities of 5 to 30 times that produced during metal-arc welding, the following safety measures to be followed: 1.The use of chlorinated solvents shall be kept at least 200 feet, unless shielded. Ultraviolet rays given off by welding can react with chlorinated hydrocarbon solvents, such as trichloroethylene, 1,1,1,- trichloroethane, to form phosgene gas (deadly) 2.Employees in the area not protected from the arc by screening shall be protected by proper filter lenses. 3.Wet working conditions must be avoided because water is an excellent conductor and electricity will always follow the path of least resistance.

73. 29 CFR 1910.255 Resistance Welding The weld is made by a combination of heat, pressure, and time. It is the resistance of the metal to be welded to current flow that causes localized heating in the part. The pressure is exerted by the tongs and tips. The time is how long current flows in the joint

76. 29 CFR 1910.255 Resistance Welding All doors and access panels of all resistance welding machines and control panels shall be kept locked and interlocked to prevent access, to live portions of the equipment. All press welding operations, shall be effectively guarded by use of a device such as an electronic eye safety circuit, two hands controls, ….

77. Continued The hazard of flying sparks shall be eliminated by installing a shield guard of safety glass or suitable fire-resistant plastic at the point of operation. Two or more safety emergency stop buttons shall be provided on all special multispot welding machines. Wear safety goggles or a face shield and heat resistance gloves.