an overview of remanufacturing marine components

Component Remanufacture In the Marine Industry

SpiralWeld® has recovered components from various marine organisations and individual owners, we have a long history of remanufacturing with a documented system going back over 25 years. This presentation will consist of five mini case study examples showing the recovery of:

o Propeller shafts o Stern seals o Rudder stocks o Stabiliser stocks o ‘Z’ type drives, including outboard motors

Introduction

Function and causes of damage:

∗ The prop shafts primary function is to transfer torque from the engine to the propeller in order to drive the boat through the water.

∗ The sheer stress from the torsion can cause the prop shaft to bend or fail. Further damage to the prop shafts is caused by corrosion, or wear, a result of operating in sea or silted water conditions and using the water as its primary lubricant.

∗ Damage like this is a common occurrence with prop shafts and when the prop shaft is replaced with an identical one, similar recurring damage is inevitable.

∗ However SpiralWeld® can provide ReManufacture+™ services to sustain the in-service life of the components and improve corrosion resistance.

Propeller Shafts

Propeller Shafts

SpiralWeld produced CAD drawing

Damaged Propeller shafts

Damaged Propeller shafts

Propeller shafts

An example of worked carried out on such a component is as follows: o ReManufacture+™ o SpiralWeld® Overlay in a high nickel alloy (total

damaged area overlaid was 937” Diameter x 49” long)

o Slow cool in thermal insulation o Proof machine then NDT with dye penetrant to

prove weld integrity o Finish machine to standard dimensions

ReManufactured™ Propeller shafts

ReManufactured™ Propeller shafts


∗ The stern seal has to function efficiently and reliably under often strenuous and unpredictable sea conditions.

∗ Its primary function is to prevent the river / sea water entering the vessel, but conversely preventing lubricants from entering the water.

∗ Damage to the seals is usually caused by a combination of corrosion and erosion from water borne particles multiplying the effect of the friction.

∗ This can be generated between the rotating propeller shaft and the seal components or between seal components, depending on the design used

Stern Seals

Stern Seals


Damaged stern seals

Damaged stern seals

Stern Seals

An example of worked carried out on such a component is as follows: o Remanufacture +™ o Pre-weld machined, NDT inspected, then

overlaid with high nickel alloy o Finish machined o NDT (dye penetrant) o Ultrasonic examination as required.

ReManufactured™ stern seals


∗ The rudder stock is the shaft/spindle which connects the rudder to the boat’s steering mechanism.

∗ It is a vital component in the safe operation of the vessel and reliability, together with a long service life, is required.

∗ The rudder stock can become damaged due to several factors, including wear, corrosion and physical damage.

∗ The rudder stock is subjected to re-occurring torsional stress as well as to corrosion and wear.

Rudder Stocks

Rudder Stocks


Damaged Rudder stock

Damaged Rudder stock

An example of work carried out on such a component is a follows:

∗ Remanufacture +™ ∗ The rudder stock had a damaged area of 3”

diameter x 8” long ∗ Full inspection, including NDT for cracking and

production of CAD drawing. ∗ Pre-machine ready for SpiralWeld® overlay ∗ Dye penetration inspection to determine integrity

of parent metal ∗ SpiralWeld® overlay ∗ Proof machine and dye penetration test ∗ Finished machined to correct tolerances.

Rudder Stocks

ReManufactured™ Rudder stock


Function and causes of damage: ∗ The stabiliser stock’s function is attach to and control the stabiliser blade/ fins which

stabilises the vessel as it travels through rough or turbulent water. ∗ If the ship starts to lean too much to one side then a sensing system will adjust the

stock stabiliser blades / fins to counteract the motion, causing the vessel to right itself.

∗ The damaged usually occurring on the stabiliser stocks can be caused by corrosion, erosion and wear.

Stabiliser Stocks

Stabiliser Stocks

An example of work carried out on such a component is as follows: o Remanufacture +™ o Fully inspect component and produce CAD drawing. o Recovery area: 7.10″ diameter x 20.65″ long (shaft

OD) o XRF analysis to determine metal composition of

component o SpiralWeld® with a high nickel alloy. o Finish machine to suitable tolerances and finish. o NDT to determine integrity of the SpiralWeld®

overlays by DPI or UT. o Complete Quality Assurance documentation as

required.


Causes of damage: The gear shafts are usually damaged due to two reasons:

∗ Firstly because of friction between the seal and shaft. The seal begins to wear away

allowing lubricating oil to escape and water to enter, degrading the rest of the oil. This causes wear and corrosion to the rest of the assembly.

∗ Secondly, where the shaft is left immersed for some time in water, the outer lip seal turns static and becomes depleted in free oxygen. This causes the surface of the stainless steel to corrode and become rougher where the seal operates.

The Remanufacture+™ service can fully restore the gear shaft and then overlay it in a corrosion resistant material helping to sustain the life expectancy of the component. During service, the surface is ‘work hardened’ by the lip seal working against it, leading to a longer service life; so it is much more resistant to corrosion and most importantly has an extended ‘Mean Time to Failure’ compared to an OEM part

Outdrive (Z type) Prop Drives (gear shafts)


Damaged Gear shaft

Damaged Gear shaft


An example of work carried out on such a component is as follows: ∗ ReManufacture+™ ∗ Area of damage 2” Diameter x 1” long ∗ XRF analysis ∗ SpiralWeld®overlay of high nickel/chrome alloy

layer ∗ NDT dye pen




This case study has set out to give an overview of some of the different components SpiralWeld® have recovered for the marine industry. In all instances the components could be recovered and improved with savings of up to 80% of the OEM cost. As well as providing recovery methods for these components there are various other components that also can be recovered. If there is any more information you require please feel free to contact us.

Conclusion

Tel: 02380 228801 Email :[email protected] www.spiralweld.co.uk

an overview of remanufacturing marine components

Engineering