Boiler Spares

Boiler Spares

Boiler Spares are essential to the efficient running of any boiler. Prudent maintenance with quality value for money parts extends the life of your boiler.

Turning to the OEM for your Boiler Spares can be expensive. John Moncrieff offers a range of quality, value for money Boiler Spares that are used by maintenance firms and end users alike. Our products can be found in many hundreds of plants in over 90 countries world-wide and are compatible with all major boiler types.

Boiler Sight Glass | Options


Packing Sleeves are used in many brands of Gauge Cock, to prevent leakage and to ensure effective operation. Moncrieff Packing Sleeves are made from 99.5% pure graphite with stainless steel eyelets, the computer controlled compression ensures a standard, quality product.

Boiler Sight Glass Packing Sleeves
Boiler Sight Glass Rubber Cones


In order to seal your glass tube you will need a rubber cone or square section rubber to seal. The attached link contains a comprehensive list of rubber seals, but please check with us first to ensure we have stock.

Neoprene Rubber or Viton are available.


If you are working with steam, hot alkaline, or acidic solutions a mica shield is the best way to protect the integrity of your gauge glass. Over time these liquids will wear down even the toughest gauge glass causing it to eventually crack, or have what looks like a melted appearance. A mica shield helps to prevent corrosion and extends the lifetime of the gauge glass. Moncrieff provides an array of different mica shields in various sizes so you can find the purity, durability, and size that you need for your equipment or application.

Mica shields are divided into different quality groups, as well as different sizes, through a visual inspection. The mica shield that you need depends on the type of process fluid you are working with and your application. Mica shields at the highest quality level, designated by V1, are clear and flat providing the highest level of visibility as well as protection. V1 mica is not obstructed by cracks, air pockets, colors or other factors.

V2 mica shields are slightly colored, and are considered to be navy-grade quality. The most common choice of grade suitable for most applications, whilst being economical in price are V4 mica shields. These will have more noticeable discoloration, and may contain some air pockets and a slightly wavy appearance. These mica shields still provide suitable protection from steam and alkaline solutions, but have some reduced visibility.

Please contact us for additional information.

Boiler Sight Glass Mica Shield


Information coming soon.

Boiler Sight Glass Valve Spares / Die Form Rings


Die Formed Packing Rings are an essential parts of any valve. Fitting around the spindle the ensure it’s smooth action and the prevent leakage. The effective sealing properties, combined with the ease with which it can be removed and replace ensure graphite is the material of choice.

Moncrieff rings are designed to suit every brand of valve from the smallest up to the largest globe and gate valves. With over 40,000 types of valve on the market. If we don’t have them in stock we can make them for you.

Moncrieff seals can be used to seal hot water, high temperature and pressure steam, heat transfer fluid, hydrogen gas, ammonia, organic solvents, hydrocarbons, cryogenic liquids etc.


We can supply a range of branded and unbranded replacement piston valve packing for Klinger valves. Our prices are very competitive.

Boiler Sight Glass Klinger Piston Valve Rings
Boiler Sight Glass Manhole And Handhole Gaskets


Moncrieff Gaskets are manufactured from a unique combination of non asbestos material, rubberized, with inconel wire insertions and coated in graphite. The gaskets are suitable for sealing boiler doors and can operate at pressures up to 350 psi and working temperatures to 500 Deg F, (250 Deg C). Sizes are available to suit all boiler types.