Resource Library

clear search

How can corrosion or staining of machined aluminium bronze components be avoided during shipping?

The key is to clean them thoroughly, remove water, protect them and keep them dry, so:

  1. After cleaning dry thoroughly using a dewatering fluid such as WD40.
  2. Remove displaced water with forced warm air.
  3. Coat with a protective coating such as benzotriazole inhibitor, or a block co-polymer.
  4. Pack into benzotriazole treated paper lined wooden boxes. Moisture absorbent granules may also be used to keep the air inside the boxes dry.

When unpacked, remove the coatings with a phosphoric-based solution and dry them thoroughly.

Is it possible to heat treat aluminium bronze CW307G (CA104) to improve its corrosion resistance?

Yes, this is covered in Def Stan 02-833. For extruded rods and sections of size 40mm and below, an anneal at 740°C plus or minus 20° followed by air cooling is carried out. This mandatory heat treatment is to eliminate phases which are likely to give rise to selective corrosion in sea water.

How can corrosion or staining of machined aluminium bronze components be avoided during shipping?

The key is to clean them thoroughly, remove water, protect them and keep them dry, so:

  1. After cleaning dry thoroughly using a dewatering fluid such as WD40.
  2. Remove displaced water with forced warm air.
  3. Coat with a protective coating such as benzotriazole inhibitor, or a block co-polymer.
  4. Pack into benzotriazole treated paper lined wooden boxes. Moisture absorbent granules may also be used to keep the air inside the boxes dry.

When unpacked, remove the coatings with a phosphoric-based solution and dry them thoroughly.

Guide to Nickel Aluminium Bronze for Engineers - Pub 222

Guide to nickel aluminium bronze for engineers wishing to specify, design or produce nickel aluminium bronze components for marine, aerospace and other sectors. 2018. 100 pp.

Download document

The Corrosion Performance of Metals for the Marine Environment: A Basic Guide (European Federation of Corrosion (EFC) Series)

This book, edited by Carol Powell and Roger Francis, is aimed at engineers new to the marine environment and those wanting to update their knowledge. Applications, commonly used alloy compositions, mechanical properties and the types of corrosion that the alloy groups are susceptible to are all described. The concluding section provides an explanation of galvanic corrosion in seawater and how each alloy group behaves when coupled to others

Go to link

I am designing a rope guide in brass for a racing yacht. Which brass and manufacturing method should be used? Is chromium plating essential?

To resist the bending stresses in service, a high-tensile brass such as CW721R (CZ114) should be used. There is no need to chromium plate since it will increase the cost by 50% and is in any case merely decorative. Depending on the numbers required hot stamping (forging) could be used to make the component to near net shape.

We have supplied copper nickel tubes to the UK from overseas. The wooden boxes containing the tubes became saturated with rain water at the port of exit and on arrival in the UK were heavily tarnished (green). Is there any way of cleaning the tubes?

If the oxide is tenacious grit blasting may be required. This should be followed by pickling in a hot 5-10% sulphuric acid solution containing 0.35g/litre potassium dichromate. The pickled tubes should be rinsed thoroughly in hot fresh water and finally dried in hot air.

What are the critical pitting and crevice corrosion temperatures for copper-nickels in chloride environments?

Copper-nickels do not behave in the same way as stainless steels do towards corrosion by chlorides and these parameters are not appropriate to them. They do not have a critical temperature limit.

What types of corrosion are copper-nickels sensitive to?

It is important that maximum velocity guidelines are adhered to for piping and heat exchanger/condenser service, as high velocities can cause impingement attack. Exposure to sulphides and ammonia in polluted seawater can lead to pitting or high corrosion rates and it is important to avoid these conditions, particularly during commissioning, start up and standby.

I have a number of machined aluminium bronze components which are to be packed in wooden boxes and shipped to Australia. How do I avoid corrosion/staining?

The key is to clean thoroughly, remove water, protect and keep dry:

1. After cleaning dry thoroughly using a de watering fluid such as WD40.
2. Remove displaced water with forced warm air.
3. Coat with protective coating such as benzotriazole inhibitor or a block copolymer.
4. Pack into benzotriazole treated paper lined wooden boxes. Moisture absorbent granules may also be used to keep the air inside the boxes dry.
5.Remove the coatings with a phosphoric based solution.
6. Dry thoroughly.

What copper alloy is recommended for condenser tubes cooled by seawater?

90/10 (or 70/30) copper-nickel alloys.