5. Safe Handling of TDI Products

TDI and some products containing TDI are reactive and potentially hazardous chemicals. Prospective new customers must complete a BASF TDI Prequalification Questionnaire prior to their first shipment. This returned questionnaire is evaluated to ensure the customer can safely handle TDI. TDI should only be handled by knowledgeable, well-trained personnel who thoroughly understand the hazards associated with the transportation, storage, and use of the chemical. Eating, drinking and the use of tobacco products should not be allowed where TDI is handled or stored. Contaminated clothing must be washed before reuse. Discard severely contaminated
clothing. Never reuse contaminated footwear or leather gloves.

 

Employee Training and Education

The investment in employee education and training on proper storage and handling procedures for TDI is extremely important. Hazardous situations may be created by poorly trained personnel even in well-designed operations. All personnel who may come in contact with TDI products should be included in a hazard communication training program. Employee training and education programs must include the regulations of all applicable agencies. Local regulations must be obtained from local authorities. Additional information is available at: https://polyurethane.americanchemistry.com/Products-Resources-and-Document-Library/ 

Operating procedures, including all safety rules should be reviewed by all personnel regularly. Safety procedures and rules should be posted in work areas accessible to all individuals. Safety equipment should be available and maintained in good working order.

 

Engineering Considerations

Building design considerations can reduce the potential hazards associated with the storage and handling of TDI. Careful consideration must be given to the design of the building’s ventilation system. TDI aerosols and vapors must be monitored and controlled below applicable regulatory limits. If possible, TDI should be processed within closed systems. When this is impractical, as in most slab foaming operations, wood production and laboratory areas, special consideration should be given to ventilation design and respiratory protection in these applications.

Regulations involving hazardous chemicals are continually evolving and thus exposure guidelines are reviewed regularly and modified whenever new information dictates change. It is important that all companies handling TDI products are aware of the current legislative requirements in each jurisdiction.

The guidelines established by OSHA, ACGIH, NIOSH, and others represent current thinking and are believed to be conservative and protective of occupational workers. There is no guarantee of absolute safety.

Additional precautions

Care should be taken to prevent the contact of water with TDI. Water reacts readily with TDI and is the most common contaminant of diisocyanates. The hazard associated with this reaction is associated with the formation of CO2 and the resulting increase of pressure in closed containers. Even small quantities of water can cause significant problems and the following safety recommendations must be observed:

• Store TDI in a dry environment using dry nitrogen or a dry air or nitrogen pad. Dry air or nitrogen should have a dew point below –40°C (-40°F).
• Plug and cap all lines leading to and from storage tanks.
• Fittings and line connections should be maintained and stored in a dry environment.
• Do not tightly close any container of TDI that has been, or is suspected of having been, contaminated with
  water.

Contamination by basic compounds such as caustic soda, amines, or other similar materials must be avoided. The reaction of TDI with these materials may cause the generation of heat and CO2. The liberation of CO2 in tightly closed or restricted vessels or transfer lines may result in a violent rupture.

 

Personal Protective Equipment

Personal protective equipment (PPE) is not an adequate substitute for safe working conditions. However, in many instances including emergency situations, it may be the only means of protecting the worker. Only individuals wearing this equipment are protected. Unprotected personnel should be removed from any work area where there is a potential for exposure to TDI.

Eye protection

Chemical safety goggles are required for all persons handling TDI, especially where there is a possibility of splashing, spraying or TDI-coated dust. Cup-type or rubber-framed goggles equipped with the approved impact resistant glass or plastic lens are recommended.

Respiratory protection

TDI vapor concentrations exceeding permissible exposure levels (PEL’s) may occur. Such occasions include (but are not limited to) the following:

• Spray operations
• The opening of tank car hatches, truck manway covers, or drum plugs
• Connecting or disconnecting of hoses and pipes
• Equipment operation or repair
• The breaking, or failure, of TDI piping or equipment
• Any spill or leak of TDI

Personnel must not enter an area where TDI vapor concentrations or aerosols may exceed the recommended exposure limits without appropriate PPE. Personal protective equipment must be worn whenever exposure to TDI vapors is possible and should not be removed until adequate ventilation is confirmed.

Respirators must be approved by all applicable authorities and a written respiratory protection program with medical surveillance must be implemented. In the United States, an air-purifying respirator (APR) can be used provided that (1) the respirator is equipped with an end-of-service life indicator (ESLI) certified by NIOSH for the contaminant, (there are no ELSI for TDI) or (2) If there is no ESLI appropriate for conditions in the workplace, the employer implements a change schedule for canisters or cartridges that is based on objective data that will ensure that canisters and cartridges are changed before the end of their service life. Therefore, an employer must select a cartridge or canister recommended by the manufacturer and must then implement an appropriate change out schedule. The data relied upon and the information forming the basis of the determination must be included in the employer’s written respiratory
program.

If APR’s cannot provide appropriate protection, respiratory equipment must be an air-supplied (SAR) or self-contained breathing apparatus (SCBA) with full-face piece operating pressure-demand or other positive pressure mode.

Respiratory protection equipment must be carefully maintained, inspected, and cleaned regularly. Location of equipment should be easily accessible, and personnel should be thoroughly trained on the proper selection, maintenance, and use of equipment.

Head, Skin, Hand, and Foot Protection

Head protection should be worn to protect from falling objects, overhead leaks, and splashes. A long sleeved, impervious protective suit should be worn whenever there is the possibility of exposure to TDI. Impervious gloves should be worn whenever the possibility of spills or splashes exist. See the Center for the Polyurethanes Industry (CPI) website (http://www.polyurethane.org) for recommendations on
glove permeation data.

Personnel handling TDI drums and cans should wear protective safety shoes with built-in steel toecaps. Rubber overshoes may be worn with ordinary work boots. Never wear uncovered leather shoes. Leather will absorb TDI, making decontamination of leather products such as gloves or shoes difficult.

Surfaces should be thoroughly washed with soap and water after mild contamination

 

Fire Hazards

Due to its high flash point (135ºC / 275ºF), liquid TDI does not constitute a severe fire hazard. However, it is important that the proper fire-fighting equipment be available in case it should be needed.

Water spray is effective for extinguishing fires covering large areas. Automatic sprinkler systems may be helpful in certain applications. When water is used to extinguish TDI fires, it should be applied in large amounts. Small amounts may only react with the hot TDI and worsen the fire situation. CO2, protein foam, or dry chemical extinguishers are also effective.

Do not inhale gases or fumes from burning TDI, as they can contain carbon monoxide, nitrogen oxides, TDI, and small amounts of hydrogen cyanide.

Fire fighters should wear self-contained breathing apparatus. Appropriate personal protective equipment (PPE) should be worn – including a turnout coat, gloves, boots, and helmet.