Corrosion Protection

Users of older Hammond Manufacturing catalogs will have noticed a change to the ratings noted for Type 4 painted mild steel enclosures. Previously, Hammond catalogs have shown that these enclosures also carried the Type 4X designation, but this is no longer noted in the catalog. There has been NO CHANGE WHATSOEVER to the quality of the Hammond paint Finish.

Hammond has removed the 4X approval from the catalog only to avoid mis-application of painted steel enclosures. The testing criteria for Type 4X is not as rigorous as many users may assume. It is important for users to understand the NEMA 4/4X rating. In response to concern about the costs of corrosion, the Underwriters’ Laboratory (UL) and the National Electrical Manufacturers’ Association (NEMA) have developed a rating system for electrical enclosures, stipulating that certain minimum conditions of corrosion resistance be met. Material tested to UL1332 (type 4 protective coating) is prerequisite to a type 4X salt spray test.

The NEMA 4X rating is applied to material that has met, under laboratory conditions, a six hundred hour salt spray with no worse pitting than that exhibited on a Type 304 Stainless sample run at the same time. This rating, however, does not test for corrosion resistance beyond this, or with chemicals other than salt.

Corrosion Resistance of Various Enclosure Materials*

Material Suitability
Limited Satisfactory High
Steel - Powder Paint
Stainless Steel Type 316
Stainless Steel Type 304
Steel- Powder Paint
Stainless Steel Type 316
Stainless Steel Type 304
Stainless Steel Type 316
Stainless Steel Type 304
Steel Powder Paint

Acids: Hydrochloric acid, nitric acid, sulphuric acid, acetic acid, magnesium, chloride, sea water
Alkalies: Sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonia, pyridine, hydroxylamine, methylamine
Solvents: Acetone, ethyl alcohol, lacquer thinner, methylene chloride, mineral spirits, turpentine, toluene, unleaded gasoline, xylene

* This chart provides a quick reference but does not address material concentration levels or other environmental impacts.

Suggested Applications for Corrosion Resistant Enclosures

Material Type Hammond NEMA Rating Suggested Application
Stainless Steel Type 304
Indoor/outdoor Applications. Ideal for hose-down and wet areas (eg. food processing, water treatment, dairies, breweries, etc.)
Stainless Steel Type 316
Indoor/outdoor Applications. Ideal for most environments, especially marine.
Indoor/outdoor Applications. Ideal for marien
Fiberglass Reinforced Polyester
Indoor/outdoor Applications. Ideal for continually wet, cold, or salty environments. Also useful in solvent or chemical laden areas. Strong resistance to heat, dilute acids and bases, impact, fire and outdoor exposure.

Pre-Treatment and Paint Process

Hammond offers a number of standard colors including ASA 61 gray, RAL 7032 and panel white. The ultra durable powder paint is applied to a multi staged degreasing, rinsing and phosphating undercoating. Hammond standard finishes can be re-painted and detailed recoating information is published in catalogs and also included with insert sheets shipped with the product.Hammond has established, documented, implemented, and maintained a quality management system and has continually improved its effectiveness in accordance with the requirements of the ISO 9001:2000 International Standard.

Process Function
Wash & Rinsing
Cleaning solution aids rinsing agents, prepares surface for conversion coatings.
Phosphating Coating
Corrosion protection agent plus surface prep for superior paint adhesion
Powder Coating
Electrostaticly applied for uniform coverage on all surfaces edges and recessed areas
Bake Cycle
Baked for up to seven minutes at 400°F
Wash, Rinsing
Phosphate Coating Line
Powder Painting

Powder Coating Reference Chart

The majority of enclosure suppliers, including Hammond, utilize polyester powder paint in their 
manufacuturing process.

Properties Epoxy Hybrid Polyester Polyester TGIC* Polyurethane
Outdoor Weathering
Poor Fair Excellent Good
Chemical Resistance
Excellent Good Good Good
Excellent Excellent Excellent Excellent
Solvent Resistance
Excellent Good Good Fair
Hardness - Scratch Resistance
Excellent Good Good Good
Good Good Excellent Good

*Hammond Powder Coating
The performance of the various paints listed above can change and is dependent on the variety and effects of the different acids and solvents used.