Generator inlet and exhuast valve &seat ring repalcement need proceed properly with manual procedure which often be ignored by engineers, Here follow is one case we workshop ever done for WARTSILA Generator for engineer reference.
1 Removal of the old ring
The exhaust seat ring can most conveniently be removed hydraulically
valve can be used.
1 Fit a scrapped valve to the seat and weld it to the seat by means of electric beam welding. Preferably the valve disc
should be machined to proper size to get a better welding.
2 Press or knock out the ring but be careful not to damage the valve guide.
2 Fitting a new inlet valve seat ring
1 Check the bore diameter in the cylinder head.
2 The ring can be assembled by freezing in with liquid nitrogen of -190°C, the cylinder head temperature being min.20°C, or by pressing in with a guided arbor.
3 Check the eccentricity of the sealing face in relation to the valve guide, and if it exceeds 0.1 mm, the seat surface must be ground in a seat grinding machine
3 Fitting a new exhaust valve seat ring
1 Clean the bore carefully with a grit 400 or finer emery cloth.
2 Check the bore diameter in the cylinder head, see section 06.2 in this manual.
3 Cool the seat ring to -20 – -25°C prior to fitting. Note that a temperature lower than -25°C may damage the O-rings at mounting.
4 Heat up the entire cylinder head to 100°C by means of either steam heating, e.g. put the cylinder head into a closed box, or a gas burner.
It is important that the entire cylinder head is heated up, not
only the seat bore.
5 Mount the O-ring(s) on the cooled valve seat.
6 Apply soap-water solution to lubricate the o-rings.
7 Mount the exhaust valve seat by using one of following methods:
• Put the seat rings into a guiding bush and press in the seat with a guided arbor. A special tool is also available.
This tool can be ordered from the engine manufacturer.
• Insert the seat ring by using an exhaust valve. Knock on the valve until the seat ring is correctly seated.
Mounting of a exhaust valve seat ring should be done carefully so that the seat ring is correctly seated.
8 Check the eccentricity of the sealing face in relation to the valve guide, and if it exceeds 0.1 mm, the seat surface should be ground in a seat grinding machine.
9 Pressure test the cylinder head water side before mounting with a test pressure of 10 bar if possible.Use pressure test tool for blocking the water holes of cylinder head.