ASME Standard 111-1960 — Recommended Practices for the Design of Marine Propulsion Turbine Lubricating Systems

⚙️ ASME Standard No. 111 (1960), officially titled Recommended Practices for the Design of Marine Propulsion Turbine Lubricating Systems, was prepared by Panel II of the Joint ASTM-NEMA-ASME Committee on Turbine Lubrication. The document consolidates the experience of equipment builders, ship designers and builders, classification societies, government agencies, and lubricant suppliers into a set of consensus design practices. Published by The American Society of Mechanical Engineers, the practices are presented as minimum requirements and a guide for the marine industry, and they profoundly influenced the design of shipboard propulsion machinery for decades after publication.

1. Background and Purpose 📌

The introduction notes that turbine oils with improved properties had been under development for many years, and that test methods had been established to evaluate the various characteristics of these oils. While such test methods generally assure the ultimate user of receiving a satisfactory oil, they alone do not guarantee satisfactory service performance. Experience demonstrated that system design, operating conditions and practices, and oil quality are closely interwoven, and that each contributes a part of the specified performance requirement.

To improve the design of marine turbine lubricating systems, representatives of the industry therefore developed the recommended practices presented here. They are considered minimum requirements. The Standard also announces that, subsequent to this issue, recommendations would be issued on oil handling and purification, flushing and cleaning, and on the design of lubrication systems for ship service turbo/generators where they affect the main system.

2. The Three System Types 🛢️

The recommendations are organized around three groups of systems, and each is treated separately in detail:

• Gravity system — the oldest and most widely used of the three. By its inherent design it provides maximum safety and reliability, and it is favored where space and weight limitations as well as damage control are primary considerations.
• Pressure system — oil is delivered to the bearings and gears directly by pumps, allowing a more compact arrangement.
• Pressure/gravity system — exists in two types, a high-elevation system and a low-elevation system, both being consolidations of the pressure and gravity concepts. The high-elevation system is a variant of the gravity system, while the low-elevation system is employed where head room is limited, as on Great Lakes ships.

3. Material Selection Requirements 🔩

Materials directly affect both oil life and system integrity. The Standard gives specific guidance:

Materials for system components must also be selected with vibration and shock considerations in mind, reflecting the roughest operating conditions a ship can encounter.

4. Piping, Valves, and Coolers 🛠️

For piping, the Standard requires welded or flanged-and-bolted connections. Screwed or threaded connections are not recommended; where unavoidable they must be seal-welded. Piping must be adequately braced against vibration, and all oil piping must be constructed and located so that it is protected from hot surfaces — there must be no possibility of oil leaks impinging on hot surfaces. Take-down joints should be conservatively designed and readily accessible, instrument connections should be designed and installed for maximum safety with adequate bracing, and overstressing of piping and root connections must be avoided by proper consideration of differential movement caused by thermal expansion and hull warping.

For valves, the Standard requires that they be located so as to be easily accessible and replaceable. Any valve whose position is such that it will stop oil flow to the machinery must be provided with locks to guard against inadvertent closure, and all valves for draining main oil storage and settling tanks and the sump must be locked closed. For oil coolers, the sizing must maintain the oil outlet temperature at values recommended by the machinery manufacturers. Twin coolers are recommended for single-screw ships; for multi-screw ships one cooler per shaft is considered adequate. Cooler bundles should be readily removable, inlet and outlet thermometers should be installed for adequate visibility, thermostatic controls may be considered, and drains and venting provisions are recommended.

For cold starts or flushing, provisions must be made for proper heating of the lube oil — for example, low-pressure steam coils in the settling or gravity tanks, or low-pressure steam in the oil coolers. Precautions must prevent overheating of the oil or excessive steam pressure. For straining, duplex strainers equipped with magnets are recommended, enabling one basket to be serviced while the other remains in service.

5. Fire Hazard Minimization and Oil Purification 🔥

The importance of minimizing fire hazards aboard ship through proper design, material selection, and location cannot be overemphasized. The elimination of any possibility of oil contacting hot surfaces is the guiding principle. Typical measures include installing serviced components such as strainers in safe locations, and keeping pressure piping, take-down joints, and other openings well removed from sources of ignition. Because an oil jet can travel a considerable distance, the layout must account for the full reach of any potential spray.

On purification, the oil purification system must be of sufficient size to handle the oil while the vessel is under way; details are described in a separate companion publication, reflecting the Committee’s plan to expand these recommended practices over time.

6. Engineering Practice Essentials ✅

• 🔍 System selection: weigh safety, reliability, space, and weight requirements first; choose between gravity, pressure, and pressure/gravity designs; use the low-elevation variant where head room is limited.
• 🔧 Material compatibility: keep copper, zinc, and lead out of oil-contact surfaces; specify high tin-base babbitt bearings; select gaskets and seals rated for oil at up to 200°F.
• 📐 Piping layout: prefer welded or flanged joints; return lines remote from the pump suction aid deaeration; locate the pump suction about 10 inches above the sump bottom for immersion under pitch and roll while reducing pickup of contaminants.
• 🗝️ Valve administration: lock any valve that can stop oil to the machinery and all drain valves; formalize the lock-out procedure.
• 🌡️ Temperature control: hold cooler outlet temperature to the manufacturer’s recommendation, use readable thermometers, and preheat the system with low-pressure steam before cold starts.

7. Frequently Asked Questions ❓