Blair Rubber Company > HCl Acid Linings
HCl Acid Linings
Superior Quality Linings For Hydrochloric Acid & Tank Linings
Hydrochloric acid (hydrogen chloride), or as once named muriatic acid, is a strong, highly corrosive acid. The commercial "concentrated" or fuming acid contains 38% hydrogen chloride. U.S.P. grades range from 28 to 38%, with 37% HCl being most common. Blair Rubber's personnel are experienced in designing and processing rubber compounds for the highly corrosive environments encountered in various HCl acid applications.
For storage tanks, tank trailers and tank cars, natural rubber lining on steel has predominantly been used for hydrochloric acid containment. The acid reacts with natural rubber hydrocarbon to chlorinate the surface, making an impermeable membrane. In concentrated hydrochloric acid, it only takes approximately three months for natural rubber crust formations to be in the range of 1/64 (.016") thickness in depth. This crusting effect makes natural rubber an excellent lining for HCl. It is also the destructive mechanism of the lining in later years. As surface stress cracks develop the acid penetrates the rubber, forming a new surface crust. The cycle continues until complete lining failure eventually occurs. Lining service performance ranges from 7 to 24 + years depending on lining selection, environmental conditions and vessel stresses. Marflex PG-70 has lasted for 25+ years in such conditions and has the longest documented trouble free service.
Through the years, service history has demonstrated that a pure gum natural rubber gives the longest lining life for concentrated HCl. Generally, the lower the durometer, the longer it remains flexible. For example, a 40/45 durometer natural rubber will reach 75/80 surface durometer (PG-70 a 30/35 durometer takes much longer to reach 75/80 and thus nearly doubles the long term lining life); whereas a 60 durometer compounded rubber will be 85/90 Shore "A" durometer. It is that extra hardness that impedes the rubber's ability to resist flex stresses as found in over-the-road trailers or rail cars.
VE611BN, is recommended for dilute (5-10%) HCl. In dilute acid service, the compounded natural rubber has less water absorption than gum rubber. Laboratory tests show 6-8 % less water absorption for compounded 60 durometer lining as compared to a pure gum.