HJ SIP valves
Background
Cylinder lubrication is a crucial factor for maintaining a good engine condition on 2-stroke diesel engines, as it limits the wear and corrosion on pistons and cylinders. From an economic point of view, cylinder lubrication is a significant part of the ship operation due to the fact that the lube oil price has been increasing and significantly more expensive than ordinary diesel oil. Based on this, Hans Jensen Lubricators A/S has developed HJ SIP Lubrication. HJ SIP Lubrication is a unique method within the field of cylinder lubrication that ensures an optimum distribution of the lube oil at a minimum lube oil consumption.
Functionality
SIP is an abbreviation for ’Swirl Injection Principle’ and refers to the principle of using the scavenging air swirl of the engine to distribute the lube oil. For each piston stroke the engine takes, a small quantity of lube oil is sprayed out of the HJ SIP Valves. The lube oil is sprayed into the engine’s scavenging air swirl, whereby the lube oil is distributed in a thin and even layer on the cylinder wall. Thereby, an optimum cover of the top of the cylinder wall is achieved, where the need for cylinder lubrication is largest.
Installation
HJ SIP Lubrication can be implemented on both newbuildings and vessels in operation. The necessary machining of the cylinders at installation depends on the type of HJ SIP Valve. The following types of HJ SIP Valves are available:
HJ SIP I Valve
The HJ SIP I Valve is mounted by means of stay bolts. The cylinder liners have to be pulled during the machining.
HJ SIP II Valve
The HJ SIP II Valve is mounted by means of a thread. It is not necessary to pull the cylinder liners during the machining.
HJ SIP III Valve
The HJ SIP III Valve is mounted by means of stay bolts. It is not necessary to pull the liners during the machining.
Purpose
The function of the cylinder lubrication in the ship operation is to reduce the friction between pistons and cylinder, by which the wear is reduced. At the same time, the lube oil neutralises the acid formation during combustion, which is a direct cause for corrosion.
Hans Jensen Lubricators A/S has worked on this topic for nearly a century and has thus gathered a wide experience within this field. Based on this, Hans Jensen Lubricators A/S has developed a product that contributes to a better distribution of the lube oil than traditional lube valves, while the lube oil consumption is reduced.
HJ SIP Lubrication sprays a sufficiently small quantity of lube oil into the scavenging air swirl on a 2-stroke diesel engine, whereby the centrifugal power inside the scavenging air swirl distributes the lube oil evenly on the cylinder liner. By using HJ SIP Lubrication, it is possible to reduce the operational costs for both lube oil consumption and maintenance. In addition, a reduction of the environmental impacts and the formation of oil sludge and engine smoke is obtained.
System description
The HJ SIP Valve is characterised by being adjusted to open at a given oil pressure received through the pressure pipe from the lubricator. By means of the pressure, the nozzle of the HJ SIP Valve turns a sufficiently small quantity of lube oil into a spray, which is sprayed into the cylinder.
Based on the engine’s size, an adequate number of HJ SIP Valves are mounted in the cylinder liner, so that each spray overlaps the next. The HJ SIP Valves spray lube oil into the scavenging air swirl, whereby the lube oil is distributed on the entire cylinder liner by means of the centrifugal power of the engine’s scavenging air swirl. Leak oil from the valves is lead back to the vessel’s supply tank which leads the lube oil to the lubricator.
Installation
This new technology can be applied on both vessels in operation and on newbuildings, as it in principle can be applied on all known 2-stroke engine designs. In connection with newbuildings, it is an advantage to ensure that HJ SIP Lubrication is specified from the beginning.
Retrofit on engines with timed HJ Lubricators provides interesting opportunities for savings. At installation, the traditional cylinder liners must be modified before the HJ SIP Valves can be mounted. For the HJ SIP I Valve this means machining of the liner, both inside and outside. Therefore, the installation of the HJ SIP I Valve requires that the liners are pulled. At the installation of the HJ SIP II and HJ SIP III Valves, only a minor machining inside is required and therefore it is not necessary to pull the liners during the machining.
Should the liners need to be renewed, it is an advantage to order liners which are already prepared for HJ Lubrication so that subsequent modification is not necessary.
Maintenance interval
The function of the HJ SIP Valves should be checked at appropriate intervals, e.g. when renovating a cylinder, or after every 12,000-15,000 running hours. We recommend that the spray, the closing pressure and the quantity of leak oil are checked at appropriate intervals, for example every two years. In addition, we recommend that the distance between the cylinders and the tip of the needle is measured to ensure that wear on the cylinders does not lead to an exposure of the tip of the valve which may then be damaged by the piston rings. The distance is specified in the manual for the HJ SIP Valves.
Adjustment of the closing pressure
The closing pressure inside the HJ SIP Valves is specified in the manual for the HJ SIP Valves. The closing pressure can easily be tested onboard, using an ‘HJ Nozzle test rig’ with thin oil, e.g. hydraulic oil with the viscosity index SAE 15-20.
If the closing pressure deviates from what is specified, it must be adjusted. This is done by removing the screw (17) and the cover (16) and then adjusting the adjusting screw (13). By turning the adjusting screw counter-clockwise the pressure is increased and by turning the screw clockwise, the pressure is reduced.
Measuring of leak oil
When a measuring of the leak oil is carried out, it is recommended to dismount the return pipe (26) in the screwed connection (27) and block the return pipe. The oil flow must be stable before the measuring of the leak oil can be initiated. Due to the relatively small quantities of leak oil, the measuring should be carried out over an appropriate number of hours. At delivery, the leak oil quantity of the HJ SIP Valves is 15±10 ml/h. The leaking quantity may be increasing over time. Therefore, we recommend that the leaking quantity is checked at appropriate intervals, e.g. every second year or when renovating a cylinder.
Dismounting a valve
We recommend that the HJ SIP Valves are sent to Hans Jensen Lubricators A/S for renovation. If it is necessary to renovate an HJ SIP Valve, please follow the instructions for the concerned valve.
