the new dimension
of stainless
User Guide
for Nautical Anchor Chains
October 2014
2
General Informations for your cromox,
Anchor Chain
Your cromox anchor chain offers a multitude of
benefits. There are several considerations that
need to be taken into account. The corrosionresistance protection of stainless steel is created
by the combination of chrome and oxygen to
form chromium oxide. The chromium oxide
layer, often called the protection layer, is as a
barrier against corrosion and protects the steel.
There are many varieties of stainless steels with
considerable differences in quality. For anchor
chains, the material’s compatibility to be made
into a chain and the corrosion-resistance of the
material are of utmost importance.
1. Proper Care
For long-use of your cromox chain, the following
are strongly suggested:
•Clean the chain with freshwater in the anchor
chest before it is connected.
•The chain should be regularly cleaned with fresh
water after usage.
•Avoid constant contact with saltwater-exposed
cordage.
•Strictly avoid any contact with rusted materials.
Contact with rust particles or materials, which
may rust, can become embedded on the surface
of stainless steel chains. Rusty particles can
infect the stainless steel and rusty spots may
develop or the chain may develop a rusty-red
surface color.
•The chains’ smooth surface must be maintained.
If the chain develops or shows one or more
sharp burrs, they should be smoothed immediately
as these spots will be more susceptible to corrosion.
Last Reviced: October 2014
User Guide
•Keep the chain free from organic materials.
Anchoring in brackish water, the risk of corrosion
will increase through sediments, microorganisms
and the growth of biological layers or bio fouling.
Microorganisms embedded on the chains’ surface
and their growth can corrode stainless steel.
2. Mainte nance
d
The anchor chain should be regularly inspected.
•Before the anchor chain is inspected, it must
be thoroughly cleaned. Any type of non-corrosive
cleaning method is permissible. High-heat,
abrasive cleaning, and any method that could
hide any damages must be strictly avoided.
•Ensure sufficient lighting is used for the inspection
and all parts of the chain thoroughly and
carefully checked.
The following are reasons to take the anchor chain
out of service and conduct maintenance/repair:
u Inability to extend or deform chain links.
u The nominal thickness of the chain link
is < 90 % (Fig. 1) because of wear and tear.
d2
A
d1
A
A–A
d + d2
1
2
= < 0,9 x dn
(Abb. 1)
u Damages (cuts, burrs, furrows, cracks,
discoloration caused by heat, extensive
corrosion, bent or curved chain links or other
any defects) are observed or suspected.
4
3. Materials
Ketten Wälder uses the following materials in
cromox chain production:
1.4404, also named AISI 316L or S31603
•Compared to 1.4307, the corrosion resistance
is significantly higher.
•Excellent resistance against corrosion in natural
environmental media (fresh water, rural and
urban environments), as well as in industrial
settings with moderate chlorine and salt
concentrations, such as the food and beverage,
pharmaceutical, and agricultural industries.
•Due to the low carbon contents, this material is
resistant against intercrystalline corrosion after
welding. This material is not seawater-resistant.
1.4462, also named AISI 318LN or S31803
This steel belongs to the family of duplex steels
(DSSs). This steel is valued for its higher-resistance
against corrosion compared to austenitic steel
1.4404.
•The austenitic-ferritic structure increases the
resistance against stress - crack corrosion and
pitting even in high chlorine concentration and
low pH environments.
•1.4462’s resistance in seawater generally is
very good, but under harsh settings and improper
maintenance, corrosion cannot be ruled out.
Last Reviced: October 2014
User Guide
4. Chain Selection
The selection of anchor chain materials is guided
by the bodies of water and water temperature,
where the vessel will be anchored.
•Freshwater - 1.4404
In freshwater environments, corrosion is not of
great concern. However, in and around swim ming pools and in air, which is heavily polluted
through industry or agriculture, corrosion
cannot be excluded.
•Saltwater -1.4462
Salty coastal and sea air can lead to corrosion
on the surface of low- corrosion resistant alloys
such as 1.4307. Insufficient maintenance/hand ling of durable alloys like 1.4404 can also lead
to corrosion. In water, the chloride concentration
is the most crucial factor to corrosion susceptibility.
Sample Chloride Concentrations
Chloride Concentrations (appr.)
Groundwater and clean
10 - 40 mg/l
surface water
Surface water polluted
by raw sewage
40 - 250 mg/l
Atlantic Ocean/North Sea
19.000 mg/l
8.900 mg/l
Baltic Sea
15.000 mg/l
Dead Sea
Mediterranean Sea/
21.000 mg/l
Persian Gulf
6
Pitting-Resistance-Value/PRE
The Pitting-Resistance or PRE - Value is used for
a more accurate calculation of an anchor chain’s
corrosion resistance in chlorine media. Stainless
steels are generally regarded as seawater resistant
with a PRE - Value of at least 33.
PRE-Values:
Material1.43071.4404 1.4462
PRE-Value 16,50 – 20,26 23,10 – 28,50 30,85 – 38,07
Ketten Wälder GmbH guarantees a PRE - value of
at least 35 for chains made of 1.4462 steel.
Critical Pitting Temperature-Value
To calculate the variable water temperate on
pitting corrosion, the CPC value is used. This
value indicates the critical temperature at which
pitting corrosion can develop for each respective
material.
Material1.43071.4404 1.4462
5. Types of
Corrosion
CPT-Value
10° C
24,0 – 27,5° C 27,5 – 34,5° C
50° F
75.2 – 81.5° F 81.5 – 94.1° F
Surface corrosion
Surface corrosion seldom occurs with anchor
chains. The chain is considered resistant to surface
corrosion if the loss of material is less than 0.1g/
m2 x h or less than 0.11 mm thickness/year.
Last Reviced: October 2014
User Guide
Intercrystalline Corrosion
cromox chains are resistant against intercrystalline
corrosion.
Crevice Corrosion
Crevice corrosion occurs when crevices develop
between construction materials such as between
screw heads and bolts or between bolts and
holes. The risk of crevice corrosion is even greater
at gaps between stainless steel and plastic parts.
To avoid or reduce the risk of crevice corrosion,
the cromox chain must be properly installed.
Pinholing/Pitting Corrosion
Pitting/pinholing is the most common type of
corrosion on anchor chains. The protecting layer
of the steel becomes damaged and these areas
become more susceptible to corrosion. If the
protection layer cannot repair itself in the damage
causing water, then small holes will develop.
The small holes will be rusty in color. A reliable
indicator of pitting corrosion is the CPT - value.
d
Influencing Factors for Corrosion
The corrosion of anchor chains is influenced by
multiple factors. Deposits and sediments are most
damaging to anchor chains. Microorganisms can
initiate or even increase corrosion through their
metabolism.
8
d
Attention
Service and repair are to be conducted only by
the manufacturer.
The experts at Ketten Wälder are happy to assist
customers in their selection of the most suitable
material for their anchor chain needs.
Last Reviced: October 2014
User Guide
10
Protection Layer Certification
Warranty Check
Warranty Extended to:
Date / Stamp/ Signature
Warranty Extended to:
Date / Stamp/ Signature
Warranty Extended to:
Date / Stamp/ Signature
Warranty Extended to:
Date / Stamp/ Signature
Last Reviced: October 2014
Warranty
User Guide
Customer Information
First name
Last name
Company
Street
Postal code/City
Telephone
Purchase Date
Chain
Customer No
Code
PRE-Value
Dealer information
Company
Street
Postal code/City
Telephone
A manufacturer’s warranty only applies when
the required information is provided and an
original sales receipt is presented. Please
keep this record for safekeeping as Ketten
Wälder cannot be held responsible for lost
documentation.
Warranty
For anchor chains made of 1.4404/AISI 316L , there is no warranty against corrosion.
For Anchor chains made of 1.4462/AISI 318LN , the following warranty conditions strictly apply:
Ketten Wälder GmbH guarantees electropolished chains made of 1.4462 steel for a period of
3 years from date of purchase and tumbled polished chains out of 1.4462 for 2 years from
date of purchase. The warranty can be extended by the manufacturer if the chain is returned to
our service center in Bad Endorf, Germany for inspection by our technicians at the end of its
regular warranty period. If our technicians find your chain to be in good condition without major
damages, the warranty will be extended. Where repairs are advised, an estimate will be provided.
We can also refresh the surface protection layer for a nominal service fee.
By filing a claim under warranty, you will not be extending the warranty period.
Warranty exception clause
Excluded are any defects caused by improper usage, overloading, damage from irregular usage,
contact with rocks, corals and similar elements, as well as rust and corrosion through contact with
non-stainless steels. If the chain is used improperly, the warranty is immediately invalidated.
Liability exception clause
The manufacturer is not liable for any compensation for damages for loss, damage of any materials
of any kind, bodily injuries and similar.
Ketten Wälder GmbH
Chain Technology
Im Gewerbegebiet 5
83093 Bad Endorf, Germany
Tel + 49 (0)80 53-20 29-10
Fax +49 (0)80 53-20 29-31
[email protected]
www.cromox.eu