Laserfiche WebLink
0 0 <br /> and contents in accordance with all local,state and federal regulations. <br /> C) <br /> Tank sludge and residue may contain lead compounds and/or benzene vapors.Personnel <br /> involved in the removal of these wastes must wear appropriate protective clothing and <br /> use proper equipment. <br /> 2.2.1 Preparation of Tank Surface <br /> a) Personnel involved in abrasive blasting must be familiar with API publication 2027. <br /> b) Monitor vapor readings to ensure that no flammable vapors have accumulated.To ensure <br /> a safe working environment, continue ventilation procedures. <br /> c) If product is entering the tank through a perforation in its shell,repairs must be performed <br /> prior to abrasive blast operations. <br /> d) Abrasive blast operators must wear approved protective clothing and helmets connected <br /> to sources of clean air. To provide protection from static electricity generation and <br /> discharge,the blasting nozzle must be bonded to the work surface or otherwise grounded. <br /> e) Blast the entire interior surface of the tank until completely free of scale, rust and other <br /> foreign matter.Blast the entire surface to achieve an SSPC SP-5/NACE 1 with a minimum of <br /> 2.5 mil anchor profile. <br /> f) Abrasive blasting should not be performed if relative air humidity in the tank is greater than <br /> 85%.To adjust for excessive humidity, dehumidification equipment may be used.Consult <br /> IECC directly for additional information. <br /> g) A minimum of 90-psig air pressure must be maintained during abrasive blasting operations. <br /> Twelve to eighteen (12-18) mesh grit blasting media must be used to obtain the proper <br /> anchor profile. Separators and traps must be used to remove oil and water from the <br /> compressed air utilized to operate the blasting equipment. <br /> h) Once the abrasive blasting operation is completed, the entire interior surface must be <br /> vacuumed and/or cleaned with a fine brush or broom and blown with compressed air. <br /> 1) Under normal operating conditions,the surface should be coated within eight(8) hours of <br /> blasting and before visible rusting occurs. If dehumidification equipment is in use,and the <br /> humidity level is 40%or less, the re-coat time may be greater than eight (8) hours. <br /> 2.3 Tank Inspection and Structural Assessment <br /> 2.3.1 Conduct a visual inspection of tank's interior surface to determine if the tank is suitable for lining; <br /> monitor vapor readings to ensure a safe working environment throughout the inspection procedure. <br /> 2.3.2 During the inspection,determine the extent of any internal and/or external corrosion.Test areas <br /> suspected of severe corrosion and other randomly selected areas within the tank to determine the <br /> structural integrity of the steel shell. A brass ball peen hammer may be used to tap the tank shell and <br /> sound for thin areas. If a thin area is detected, the metal should be holed with the hammer or a drill to <br /> determine the metal thickness. Remove thin metal areas until a minimum metal thickness of 1/8"at the <br /> edge of the hole is achieved. This method of inspection is commonly used to detect corrosion in <br /> underground tanks, since corrosion typically results in pitting rather than deterioration over the surface <br /> area. In addition to the ball peen hammer technique, ultrasonic techniques may also be needed to <br /> ensure metal thickness of at least 1/8". <br /> 2.3.3 To determine the structural integrity of an underground steel tank,ultrasonic thickness gauging <br /> 2/99 <br /> Page 8 of 30 <br />