All starts with selecting suitable quality steel according to requirement. All types are not same.
Let’s find out.
Overview of Stainless Steel
Today, approximately 85% of all surgical instruments are made from stainless steel.
Stainless steel is a compound of varying amounts of iron; carbon, which is added to
give steel its hardness; and chromium, which makes steel resistant to corrosion, by
combining with oxygen in the air to form a very adherent surface film that resists further
oxidation. However, the term “stainless” is actually a misnomer; the degree to which the
steel is “stainless” is also determined by the chemical composition of the metal, the heat
treatment, and the final rinsing process.
Stainless steel may also contain other alloying elements such as nickel, magnesium,
silicon, molybdenum, sulfur, and other elements to prevent corrosion or add to its tensile
strength; because of this, stainless steel can be of varying quality in regards to its
physical properties, ie, flexibility, temper, malleability, as well as corrosion resistance.
Thus, there are over 80 different types of stainless steel; therefore, the American Iron and
Steel Institute grades steel based on its various mechanical properties and composition
using three-digit numbers, as described below.
• Stainless Steel Type 304. The most popular grade of stainless steel is 304;
it is sometimes referred to as 18-8. The 300 series designation tells one that
the grade is composed basically of 18% chromium and 8% nickel. It cannot be
hardened by heat treatment.
• Stainless Steel Type 316. The next most popular stainless for general corrosion
resistance is type 316. It also consists of chromium (16%) and nickel (10%), but
also contains 2% molybdenum. The additional alloying increases the resistance
to salt corrosion.
• Stainless Steel Type 430. This is a straight chromium type stainless (no nickel)
with 16% chromium. It has less corrosion resistance than the 300 series. As with
the 300 series, 430 type steel cannot be hardened by heat treatment.
• Stainless Steel Type 410. 410 is a straight chromium grade with less chromium
than 430 (about 11.5%). Because it has less chromium, it has somewhat less
corrosion resistance than 430, but this grade can be hardened by heat treatment.
• Stainless Steel Type 409. This grade contains the lowest level of chromium at
10.5%.
Property Benefit/Description
Corrosion Resistance Lower alloyed grades resist corrosion in atmospheric and pure
water environments, whereas high-alloyed grades can resist
corrosion in most acids, alkaline solutions, and chlorine.
Fire and Heat Resistance Special high chromium and nickel-alloyed grades resist scaling
and retain their strength, even at high temperatures.
Hygiene The easy cleaning ability of stainless steel makes it the first
choice for strict hygiene conditions, such as hospitals and
kitchens.
Ease of Fabrication Modern steel-making techniques results in stainless steel that
can be cut, welded, formed, machined and fabricated as readily
as traditional steels.
Impact Resistance The micro structure of the 300 series provides a higher degree of
toughness, from elevated temperatures to far below freezing.
Long Term Value When the total life cycle costs are considered, stainless steel is
often the most cost effective material option, because stainless
steel products complete their service life. In addition, there
is less concern about disposal since this material is 100%
recyclable.
Stainless Steel Surgical Instruments: Making the Grade7,8,9
Both 300 and 400 series grade stainless steel are used in the manufacture of reusable,
heat-stable surgical instruments, with 400 being the most common. Both 300 and
400 series stainless steel resist rust and corrosion, as noted above, have good tensile
strength, and will provide a sharp edge with repeated use. The 300 series grade steel
is typically used for non-cutting surgical instruments that require high strength; the 400
series grade steel is used in the manufacture of both cutting and non-cutting instruments.
Stainless Steel Surgical Instruments: Making the Grade
Both 300 and 400 series grade stainless steel are used in the manufacture of reusable,
heat-stable surgical instruments, with 400 being the most common. Both 300 and
400 series stainless steel resist rust and corrosion, as noted above, have good tensile
strength, and will provide a sharp edge with repeated use. The 300 series grade steel
is typically used for non-cutting surgical instruments that require high strength; the 400
series grade steel is used in the manufacture of both cutting and non-cutting instruments.
While all stainless steel instruments may appear to be of equivalent quality when they
are new, there are differences in grade quality of the metals used in their manufacture;
therefore, surgical instruments are available in three grades: premier OR grade,
intermediate OR grade and floor grade instruments. Both premier OR grade and
intermediate OR grade instruments can be used in all surgical sets because they are designed and manufactured to specifications from quality stainless steel. Premier OR
grade instruments are made to strict specifications from high-quality stainless steel;
furthermore, they are subjected to strict quality control inspections at several points
throughout the steps of the manufacturing process. Instruments in this classification are
less likely to fail after repeated uses; in addition, they should cause no tissue damage
related to their construction and finishing. With proper care, handling, cleaning, and
sterilization, premier OR grade instruments will provide years of useful life. In contrast,
lower quality instruments may be of similar design, but their specifications for steel quality
and manufacture are less stringent. Floor grade instruments are made from forgings of
lower grade metals, have wide pattern variation, and are usually plated. As a result, the
precision of the instruments’ key features is less exact than those of the higher quality
O.R. grade instruments. An inspection of these instruments when they are new may
reveal nicks, burrs, and instrument tips and jaws that often do not meet perfectly. In
addition, these instruments typically bend or break easily; because they are plated, they
can scratch, chip, and rust relatively easier than the higher quality instruments; thus,
they are considered disposable and cannot be reprocessed with OR grade instruments.
Using floor grade instruments in a delicate surgical procedure can result in unintended
tissue damage that, along with the need for tissue repair, increases the potential for
impaired healing, infection, and increased costs of care associated with prolonged
recovery. Moreover most of these instruments which may appear to be stainless steel
can be of such poor quality that they are sold as “single use”.
As noted, premier O.R. grade surgical instruments are made from 300-400 grade
stainless surgical steel and are more resistant to corrosion and wear. It is important for
perioperative personnel involved in instrument processing to remember that, if the facility
uses lower, floor grade instruments, they should not be placed in an ultrasonic cleaner
or included with OR grade instruments during processing or in instrument sets; doing so
can cause changes in the metal, due to ion transfer. These changes, in turn, alter the
reaction between the metal and chemicals used for instrument cleaning, disinfection,
and sterilization; as a result, resistance to staining, pitting and rusting may also be
compromised. Once these problems occur, even premier OR grade instruments can be
compromised, and they will no longer be appropriate for use in surgical instrument sets.