GB/T 27946-2011Limit values of hazardous substances in the air of heat treatment workplaces (English PDF)

Foreword

This standard was drafted in accordance with GB/T 1.1-2009 given rules. This standard by the National Standardization Technical Committee heat treatment (SAC/TC75) and focal points. Drafting of this standard. Shanghai Institute of Machinery Manufacturing Technology Co., Ltd., Anhui Ou Sa Health Laboratory Technology Co., On Ousa Environmental Resources Management Consulting Co., Ltd., Beijing Institute of Electrical. Participated in the drafting of this standard. Guangdong Siltronic Metal Technology Co., Ltd. Xi'an Follett heat treatment, heat treatment Tianjin Research Limited. The main drafters of this standard. Cai red leaves Jian, Tian Jing Mei, Xu Yueming, Wang Xiaobing, Lu Jun, Sun Xiaodong, Wang Zhiqiang, any praise. Participate drafters of this standard. Su Yuhui, Wanggui Mao, Yang Hongfei, Song Baojing, Xingzhi Song. Heat treatment of hazardous substances in workplace air limit

1 Scope

China's national standard for the limit values of hazardous substances in the air of heat treatment workplaces. It specifies the terms and definitions and the technical requirements for the harmful substances present in the air of a heat treatment shop, and it applies to the occupational exposure limits for those substances in the heat treatment production process. A heat treatment shop is an unusual industrial atmosphere because of what the processes deliberately use. Salt bath furnaces contain molten nitrates, nitrites, chlorides and, historically, cyanides, and they emit vapour and dust from the surface of the bath and from the parts drawn out of it. Controlled atmosphere furnaces run on ammonia, methanol, propane, endothermic and exothermic gas and their cracked products, so carbon monoxide, ammonia and hydrogen are present by design rather than by accident. Quenching in oil produces an aerosol and a smoke of decomposition products every time a hot load enters it. Nitriding uses ammonia; carburising and carbonitriding produce carbon monoxide continuously; and cleaning uses solvents and alkalis before and after the treatment itself. So the substances that have to be controlled are not the general dusts and fumes of a workshop but a specific list that follows from the processes, and a limit list assembled for engineering generally would miss most of it. The standard names those substances and sets the exposure limits for each, defining the terms - hazardous substance, concentration, workplace - on which the limits rest. It is the document a shop uses to decide what to monitor, where, and against what value. Issued on 30 December 2011 and in force since 1 October 2012.

This standard specifies the terms and definitions, technical requirements for heat treatment in the workplace and other harmful substances in the air. This standard applies to the production process of heat treatment, heat treatment in the workplace air of harmful substances in the occupational exposure limits.

2 Terms and definitions

The following terms and definitions apply to this document.

2.1 Hazardous substances hazardoussubstance Gases in the air, dust, smoke and fog, etc., respiratory or contact with the skin, eyes, and via a substance harmful to human health.

2.2 Concentrationofhazardoussubstance concentration of harmful substances Contained in the mass per unit volume of harmful substances in workplace air.

2.3 Workplace workplace Laborers with professional activities of all locations.

2.4 Occupational exposure limits occupationalexposurelimits, OELs Repeated exposure of workers in professional activities and long-term process, the vast majority of people who are exposed does not cause harmful health effects Permissible Exposure Level.

2.5 Time weighted average allowable concentration permissibleconcentration-timeweightedaverage, PC-TWA Time-weights specified 8h workday, Permissible Exposure 40h average work week.

2.6 Short-term exposure allowable concentration permissibleconcentration-shorttermexposurelimit, PC-STEL Allowable concentration short time (15min) contact in compliance with the PC-TWA premise.

2.7 Maximum allowable concentration maximumalowableconcentration, MAC In the workplace, a working day, any time can not exceed harmful substances concentration.

2.8 Total dust totaldust You can enter the respiratory tract (nose, pharynx and larynx, chest bronchi, bronchioles and alveoli) in the dust. Technically the total dust sampler according to standard Registration of all dust in the breathing zone measured.

2.9 Respirable dust respirabledust Dust particles can enter the alveoli by respirable dust standard method collected, which were 7.07µm aerodynamic diameter with , The sampling efficiency of dust particles of aerodynamic diameter 5µm is 50% of the dust.