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17-4 PH

A chromium-nickel grade of stainless steel that has excellent mechanical properties at a high strength and hardness level. Scaling and distortion are minimal. Both the strength and corrosion resistance hold up well in temperatures to 800°F, but material is magnetic.



300 series stainless steel having approximately (not exactly) 18% chromium and 8% nickel. The term "18-8" is used interchangeably to characterize fittings made of 302, 302HQ, 303, 304, 305, 384, XM7, and other variables of these grades with close chemical compositions. There is little overall difference in corrosion resistance among the "18-8" types, but slight differences in chemical composition do make certain grades more resistant than others against particular chemicals or atmospheres. "18-8" has superior corrosion resistance to 400 series stainless, is generally nonmagnetic, and is hardenable only by cold working.


304 Stainless Steel

304 is the most versatile and the most widely used of all stainless steels.  Its chemical composition, mechanical properties, weldability and corrosion/oxidation resistance provide the best all-round performance stainless steel at relatively low cost.  It also has excellent low temperature properties and responds well to hardening by cold working.


316 Stainless Steel

300 series stainless steels make up over 70% of total stainless steel production. They contain a maximum of 0.15% carbon, a minimum of 16% chromium and sufficient nickel and/or manganese to retain an austenitic structure at all temperatures to the melting point of the alloy.


316 Stainless is differentiated from 304 by the addition of addition of molybdenum and a slightly higher nickel content. The resultant composition of  316 gives the steel much increased corrosion resistance in many aggressive environments.  The molybdenum makes the steel more resistant to pitting and crevice corrosion in chloride-contaminated media, sea water and acetic acid vapours.   The lower rate of general corrosion in mildly corrosive environments gives the steel good atmospheric corrosion resistance in polluted marine atmospheres. 


Low carbon 316, know as 316L is made with the same compounds and reduced Carbon. The reduced carbon further reduces the risk of corrosion.

  • Carbon = C
  • Mn = Maganeze
  • P = Phosphorus
  • S=Sulpher
  • Si= Silicone
  • C=Chromium
  • Ni =Nickle
  • Mo=Molybdinum



To heat metal in order to lower its hardness. The term anneal refers to the heat treatment given to 300 series stainless and most 400 series stainless by the steel mill after the raw material has been completed, but before fittings are manufactured. Anneal also refers to the heat treatment given 400 series stainless fittings after their manufacture (also called hardening and tempering) to lower hardness and increase toughness. For example, fittings of 410 stainless may score over 200,000 psi after manufacture and be too brittle. By annealing at 1000 degrees F., tensile strength would reduce to 125,000-150,000 psi, while annealing the same material to 500 degrees F. would bring tensile to 160,000-190,000 psi.



Stands for American National Standards Institute.



Stands for American Society of Mechanical Engineers.



Stands for American Society of Testing and Materials.



Stands for "Break Load", meaning the weight at which a product will break. Typically, Suncor products have a minimum 4:1 safety factor. This means the  work load is 1/4 of the Break Load is 4,000 lbs so the Work Load is 1,000 lbs.



Electropolishing is primarily used to obtain a bright, clean appealing surface. However it also passivates the surface while removing burrs, sharp edges, microscopic nicks and scratches from the surface. It can smooth threads and remove heat discoloration from spot or TIG welds. Suncor products are electropolished to ASTM Standard A967.



Stretching a fitting to the point that it breaks. The percent of elongation at rupture (same as measure of ductility) is determined by dividing to total length after stretching to the original length. Elongation decreases as strength and hardness increase.


Galvanic Corrosion

An accelerated degree of corrosion occurring when two different metals are in contact with moisture, particularly sea water. All metals have what is termed a specific electric potential, so that low level electric current flows from one metal to another. A metal with a higher position in the galvanic series (see below) will corrode sacrificially rather than one with a lower position, meaning stainless, for example, will corrode before gold. The further apart the metals on the chart, the more electric current will flow and the more corrosion will occur. No serious galvanic action will occur by combining the same metals, only dissimilar ones. To prevent galvanic corrosion, use insulation, paint or coatings when separating dissimilar metals; or put the metal to be protected next to a metal which is not important in the assembly, so it can corrode sacrificially. Metals listed first will corrode due to galvanic reaction before those at end of paragraph: Magnesium, zinc, aluminum 1100, cadmium, aluminum 2024, steel and iron, lead, tin, brass, copper, bronze, monel, 304 and 316 stainless (passive), silver, titanium, graphite, gold.



Light emitting diodes, commonly called LEDs, are real unsung heroes in the electronics world. They do dozens of different jobs and are found in all kinds of devices. Among other things, they form numbers on digital clocks, transmit information from remote controls (the red light at the tip of the TV remote), light up watches and tell you when your appliances are turned on. 


Basically, LEDs are just tiny light bulbs that fit easily into an electrical circuit. But unlike ordinary  bulbs, they don't have a filament that will burn out, and they don't get especially hot. They are illuminated solely by the movement of electrons in a semiconductor material, and they last just as long as a standard transistor. The lifespan of an LED surpasses the short life of an incandescent bulb by thousands of hours.


Magnetic Permeability

Test simply determines the level of magnetism. Virtually all Suncor products have a value less than 2.5.



Molybdenum is a metal added to 316 stainless steel, sharply increasing its corrosion resistance to chlorides and sulfates especially various sulfurous acids in the pulp industry. Molybdenum helps reduce hardness and increase tensile strength at higher temperatures.



Invented by the International Nickel Co., and composed basically to two-thirds nickel, one-third copper. Monel has good strength, excellent corrosion resistance against salt water and in high temperatures, but is very expensive.



Stands for Military Standards. The overriding characteristic of MS fittings compared to commercial products is the extensive inspection and lot traceability for MS, guaranteeing the chemical, physical and dimensional qualities. While commercial fittings may look similar and happen to pass many tests given MS products, the commercial fittings lack the pedigree of guaranteed quality or chemical, physical and dimensional aspects that users who order MS fittings rely on.


Nitronic 50

(UNS S20910) Invented by the Armco Steel Company, Nitronic 50 is a chromium-nickel-manganese-molybdenum austenitic stainless steel. It remains completely non-magnetic after severe cold working or exposure to low temperatures. Sought after for its higher strength and greater corrosion resistance.



Stands for non-magnetic. Varying standards of magnetic units are applied to different metals for this designation.



Technically, passivation is not cleaning but is a process of dipping fittings into an acid solution to rapidly form a chromium oxide on the surface of the material, creating a passive film that protects stainless from further oxidation (see PASSIVE FILM). In common commercial terms (meaning non-military and aerospace), passivating means cleaning to users, and the terms "passivating" and "cleaning" are used interchangeably. A wide range of cleaning methods using different mixtures containing nitric, phosphoric and other acids or simply exposing cleaned stainless fittings to air for a period of time will result in a "passivated" condition. For properly cleaned fittings, it is impossible to determine the method of cleaning or passivation that was used. AN/MS/NAS fittings sold by SUNCOR have been cleaned, descaled, and passivated to the applicable engineering specifications.


Passive Film

The major characteristic of stainless is its ability to form a thin layer of protection called a "passive film" on its outside surface. This film results from a continual process of low-level oxidation, so oxygen from the atmosphere is needed for the passive film to exist. Once formed, it prevents further oxidation or corrosion from occurring. Even if chipped or scratched, a new passive film on stainless will form.



Removing surface impurities by using chemicals. Used mainly to clean parts prior to coating. This treatment is more aggressive than passivation.


Pitting Corrosion

Pitting indicates deep corrosion in localized spots on a fastener. Dirt or grease on certain portions of a fastener may block oxygen from that surface, thus impeding the passive film which protects stainless from corrosion.


Proof Load

A test load that a fitting must undergo without showing significant deformation. It is usually 50% +- of yield strength.


Solution Annealed (same as Carbide Solution Annealed)

A process of heating and removing carbide precipitants (carbon that has broken loose from its stainless steel solution) by heating a finished fitting to over 1,850 degrees F. and cooling it quickly, usually in water, so carbon content goes back into the stainless solution.



Swaging - pronounced (swedging)

The most common use of swaging is to attach fittings to cable or wire rope; the parts loosely fit together, and a mechanical or hydrolic tool compresses and deforms the fitting, creating a permanent joint.

Swage examples:

This fitting was cut and the wire pried out to demonstrate how swaging forms the fitting to the wire:

This fitting was cut in half to show how the wire melds with the fitting when swaged:



Class 1 threads are a loose tolerance. Class 2 threads comprise 90% of stainless fittings and are normal commercial tolerance. Class 3 threads have a stricter tolerance and tighter fit such as socket cap and set screws. No definite relationship exists between tensile strength and tightness or looseness of fit. The symbol "A" added to threads, such as 2A, means external threads (screws), and "B" means internal (nuts).



A turnbuckle is a device for adjusting the tension or length of ropes, cables and tie rods, or other tensioning systems. It normally consists of two threaded fittings, one screwed into each end of a metal frame, one with a left-hand thread and the other with a right-hand thread. The tension can be adjusted by rotating the frame, which causes both eyelets to be screwed in or out simultaneously, without twisting the fittings or attached cables.




Stands for "Work Load Limit", this is the recommended weight limit for safe use of a product.


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