MAN B&W Diesel
Press release
MAN B&W Diesel A/S
New standard in spindles
Teglholmsgade 41
MAN B&W Diesel introduces 2450 Copenhagen SV
Denmark
DuraSpindle™ and sets the Tel.: +45 33 85 11 00
Fax.: +45 33 85 10 30
benchmark in exhaust valve www.manbw.com
spindles
For further information,
Copenhagen, 20 May 2005. Since the introduction of the please contact:
Nimonic exhaust valve spindles on the larger bore MC Peter Dan Petersen
engines the Time Between Overhaul has become very long Senior Manager
PR & Documentation
indeed with more than 20,000 hours easily obtainable.
Tel.: +45 33 85 1470
Now MAN B&W Diesel has developed a new exhaust valve pdp@manbw.dk
spindle that will increase by more than 50% the Time
Between Overhaul (TBO) of all the other two-stroke
engines without nimonic spindles in its range.
Taking ten years research and development, the new
engine component, DuraSpindle, is based on a durable
alloy hard facing that is toughened through a patented
welding, rolling and heating process to prevent critical
indentation marks causing 'blow-by' and occasional
cracking on valve spindle seats as a result of the
combustion process.
Numerous tests found that welding a high temperature
resilient Ni-Cr alloy onto a stainless steel spindle would
dramatically improve the hardness and ductility of the valve
seat as well as its resistance to cracks compared to current
Co- and Ni-base hard facings including Nimonic 80A.
In the first stage of the process, the stainless steel
DuraSpindle goes through a new robotic welding
procedure where Inconel, an alloy traditionally used in gas
turbines, is welded in to the welding groove of an exhaust
spindle valve seat.
1 of 3
MAN B&W Diesel
Press release
Once the alloy has been welded in place, the DuraSpindle MAN B&W Diesel A/S
Teglholmsgade 41
is then machined after which more than ten tonnes of force
2450 Copenhagen SV
is used during the special rolling process to work harden Denmark
the Inconel weld to 500 HV. Whilst the spindle is being Tel.: +45 33 85 11 00
Fax.: +45 33 85 10 30
rolled and rotated three or four concentric grooves,
www.manbw.com
depending on the spindle size, are etched into the seat at a
depth of several millimetres. This actually further hardens
For further information,
what was, only moments earlier, a relatively ductile please contact:
material. Peter Dan Petersen
Senior Manager
The special rolling process provides compressive stresses, PR & Documentation
as opposed to tensile stresses to the component, which Tel.: +45 33 85 1470
may cause cracking in the seat area. Compressive pdp@manbw.dk
stressing significantly reduces the probability of cracking
even in the advent of welding defects.
The hard facing on the spindle seat is further hardened by
heating the material up to 600-700°C. The metallurgical
reaction, called precipitation hardening, creates a fine
network of precipitate which further hardens it to 600 HV.
Compared with an Alloy 50-type hard facing material
DuraSpindle is 20% harder and 50% harder if compared to
a spindle with Stellite hard facing or Nimonic 80A.
Harro Hoeg, the mechanical engineer within MAN B&W
Diesel’s materials research laboratory who developed the
new hard-facing: “The new process results in an overall
improvement in seat conditions and this improved service
performance is maintained for a dramatically increased
period of time."
MAN B&W Diesel, which, apart from the Nimonic spindles,
intends to stop manufacturing non-DuraSpindle exhaust
valves by the end of the 2005, has tested the new spindles
over several years in 50MC and, particularly, 60MC
engines installed in Wallenius Lines’ vessels.
2 of 3
MAN B&W Diesel
Press release
Tests began on the Don Juan in 1998 where a number of MAN B&W Diesel A/S
Teglholmsgade 41
prototype spindles were fitted to the car carrier’s 8S60MC
2450 Copenhagen SV
engine. It ran for 20,000 hours without being changed. Denmark
After MAN B&W Diesel inspected the valve seat no Tel.: +45 33 85 11 00
Fax.: +45 33 85 10 30
appreciable indentation was found.
www.manbw.com
More recently, tests have been carried out onboard
Wallenius ships Boheme and Electra. In the latter, MAN For further information,
please contact:
B&W Diesel installed two complete valves and will be
Peter Dan Petersen
removed for inspection for the first time in December after
Senior Manager
more than 28,000 running hours. PR & Documentation
Tel.: +45 33 85 1470
“Usually for this type of engine, we recommend the
pdp@manbw.dk
exhaust valve to be overhauled after 12,000 -16,000 hours.
But on the Boheme we installed a spindle with MAN B&W
Diesel’s new W-Seat design, which together with the
DuraSpindle hard facing, resulted in a substantial increase
in the Time Between Overhaul. These had been in
operation for 30,000 hours at a recent inspection where
they had no indentation whatsoever and were refitted for
continuous operation. The limiting factor will now never be
the seat of the spindle as it has often been the case,” said
Mr Hoeg.
With increased durability, reliability, extended TBOs,
together with the decreased number of seat grindings and,
therefore, maintenance costs, the DuraSpindle means it is
now possible to include planned overhauls in the normal
docking procedure.
3 of 3
