Selection Guide: Frequently Used Liquid Chemicals

Sulfuric Acid

Sulfuric acid, one of the most important, highly corrosives of all industrial chemicals, can be dangerous.

Pipe lines carrying sulfuric acid are commonly found in numerous chemical processing plants as well as other industrial facilities. This acid is one of the highest volume chemicals produced in the United States.

The hazardous nature of sulfuric acid is demonstrated by adding a drop of water to concentrated acid. This mixture creates an intense heat evolution sufficient to soften most plastic materials.

For piping systems carrying sulfuric acid, the TFE Spra-Gard® Shield is the RAMCO® Safety Shield that is specified most frequently. It can resist sulfuric acid at any concentration including the fuming form, oleum. Only this RAMCO® Shield can be used in this fashion. Others are suitable within certain limitations. At temperatures higher than 450°F (232°C), stainless steel is mandatory, although some corrosive attack and pitting may occur.

For dilute sulfuric acid, 30% or less, PPL and PPL (VUE) Spra-Gard® Shields can be used at temperatures up to 200°F (93°C). PE and PVC EconoGard® Shields are recommended at temperatures up to 140°F (60°C).

At ambient temperatures, TFE, VUE, PPL and PPL (VUE) Spra-Gard® Shields can be used for concentrated sulfuric acid, 93% or 98%. In laboratory tests at these concentrations, PVC and PE Econo-Gard® Shields suffered degradation and consequently, are not recommended.

Ammonia

Ammonia is among the chemicals considered by the Occupational Safety and Health Administration (OSHA), to be a recognized hazard and is listed as such in the agency’s “General Industry Safety and Health Standards”. Safety shields frequently are specified to protect against leaks and sprayouts in ammonia lines.

RAMCO®’s low cost PE Econo-Gard® Shield is resistant to ammonia at ambient temperatures and many of its compounds at temperatures up to 140°F (60°C). PPL and PPL (VUE) Spra-Gard® Shields can be used on ammonia lines at temperatures up to 225°F (107°C) while, the TFE Spra-Gard® Shield is suggested up to 450°F (232°C) temperatures. For higher temperatures, “304” and “316” stainless steel show excellent resistance to ammonia and most of its compounds.

Phosphoric Acid

Although the acid associated with phosphorus is usually referred to as phosphoric acid, a group of several different acids are formed from phosphorus:

metaphosphoric acid (HPO3)
orthophosphoric acid (H3PO4)
diphosphoric acid (H4P2O7)
phosphorous acid (H3PO3)

While these are considered strong acids, they are weaker than sulfuric acid. They do not have the powerful oxidizing properties of sulfuric acid and also are less volatile.

The complete RAMCO® Safety Shield product-line — except galvanized steel — is suitable for installation with these acid lines. The Econo-Gard® Shields, PVC and PE, are appropriate for concentrations up to 85% for temperatures up to 140°F (60°C).

TFE Spra-Gard® Shields are resistant at all concentrations with temperature limitations of 450°F (232°C), and the Stainless Steel Safety Shields can be used at higher temperatures.

Oxides and Hydroxides

Sodium hydroxide, also known as caustic soda, is the most important commercial caustic. Several other oxides — sodium hydroxide, lithium hydride, calcium oxide, barium (soluble compounds) — are classified by OSHA, the United States Occupational Safety and Health Administration, as recognized hazards.

Many of the RAMCO® Safety Shields are effective in shielding piping connections of these chemical lines at varying temperatures. Because of the number of chemicals in these categories, it is advisable to contact the RAMCO® Technical Services Group for assistance.

Acetone

Acetone, an important and widely used chemical, is a strong solvent that is highly flammable. It is popular as a paint and varnish remover and also is used extensively in the manufacture of various chemicals and drugs.

For systems using this chemical, Spra-Gard® Shields and RAMCO® Stainless Steel Shields are advised. While PPL and PPl (VUE) Shields may be used up to 121°F (49°C), TFE Shields may be used up to 450°F (232°C). Above this temperature, “304” or “316” RAMCO® Shields, seem particularly suitable for such applications.

Hydrofluoric Acid

Hydrofluoric acid, hydrogen fluoride in an aqueous solution, is very violent and extremely hazardous. The element fluorine, a strong oxidizing agent, reacts violently with water and is toxic.

Although this acid is not frequently used, in contact with glass it reacts intensely and consequently, is used to etch glass. Hydrofluoric acid is also used in petroleum cracking operations.

Because of the potential harm of this acid, shielding of its piping systems is strongly advised. RAMCO® PPL and PPL (VUE) Spra-Gard® Shields are recommended for concentrations up to 60% and temperatures up to 200°F (93°C). Above this concentration or temperature, only RAMCO® “316” Stainless Steel Shields are indicated.

Steam and Lubrication Oil

Other extremely dangerous conditions, in the event of a leak/sprayout, are piping systems carrying live steam under pressure or hot oil applications.

To provide effective shielding, either RAMCO® Galvanized Shields or the Navy Spray Shields are recommended.

“Liquors”

Three types of liquors (any aqueous solution of one or more chemical compounds) are used extensively in the pulp and paper industries. Black liquor, also called spent sulfate liquor, is liquid digester waste containing sulfonated lignin, rosin acids and other waste-wood components from which tall oil is made. Green liquor is a solution made by dissolving chemicals that are recovered in the alkaline pulping process in water, and white liquor is made by adding caustic soda to a sodium sulfide solution.

Because of the hazardous nature of the chemicals in these liquors, RAMCO® Safety Shields are commonly installed in pulp and paper manufacturing plants. The TFE Spra-Gard® and the VUE-Gard® Shields are the shields of choice because of their wide spectrum of chemical resistance.