Boiler mountings are the fittings that have to be on the pressure vessel itself before it can be operated: safety valve, main stop valve, feed check valve, water level gauge, pressure gauge, blowdown valve, fusible plug and manhole. Accessories are added to raise efficiency and the boiler runs without them: economiser, superheater, air preheater, feed pump. On the Cochran we surveyed six mountings sit at 180 °C.
Boilers/Cochran/Rear and steam set/This page
| Mountings | Accessories | |
|---|---|---|
| Purpose | Safe operation of the vessel | Higher efficiency |
| Fitted to | The pressure vessel itself | The gas or water circuit around it |
| Boiler runs without it | No | Yes |
| Examples | Safety valve, main stop valve, feed check valve, water gauge, pressure gauge, blowdown valve, fusible plug, manhole | Economiser, superheater, air preheater, feed pump |
| Measured here | Six items, 9,095 W at 180 °C | Economiser 18,327 W at 126 °C, feed pump 1,664 W at 100 °C |
The split matters on site because the two groups fail differently once insulation is fitted. Mountings are operated: the stop valve is turned, the safety valve is lifted for a test, the manhole is opened for internal inspection. Lagging wrapped over them is cut at the first of those operations. Accessories are opened on a longer cycle and each opening costs more.
| Element | Temp °C | Area m² | Bare W | Panelled W | Surface °C |
|---|---|---|---|---|---|
| Check (non-return) valve | 180 | 0.90 | 2,599 | 131 | 39 |
| Main stop valve | 180 | 0.60 | 1,732 | 87 | 39 |
| Safety valves ×2 | 180 | 0.68 | 1,963 | 99 | 39 |
| Manhole | 180 | 0.39 | 1,126 | 57 | 39 |
| Steam flanges ×2 | 180 | 0.34 | 982 | 49 | 39 |
| Sensor flanges ×2 | 180 | 0.24 | 693 | 35 | 39 |
| Total | 3.15 | 9,095 | 458 | ≤45 |
Temperatures are FLIR readings taken on a running boiler. Areas come from the CAD model of the same machine, uplifted for bolts and irregular geometry. Losses are ISO 12241:2022 steady state. The panelled column is capped at the 45 °C touch-safe design target, assessed to EN ISO 13732-1.
At 180 °C a mounting sheds 2,888 W for every square metre of body and flange.
| Surface °C | W / m² | Area surveyed m² | Where it was read |
|---|---|---|---|
| 100 | 1117 | 1.49 | Cochran feed pump |
| 120 | 1499 | 5.32 | Cochran front door |
| 126 | 1620 | 11.31 | Cochran economiser |
| 130 | 1704 | 5.32 | Cochran end plate |
| 180 | 2888 | 0.90 | Cochran check valve |
Each row is one of our own surveys: the measured loss divided by the CAD area of the same surface. Nothing is interpolated. ISO 12241:2022 steady state, still air, emissivity from the FLIR survey.
Mountings are the fittings the examination looks at, because they are what keeps the vessel inside its design conditions. The intervals come from the written scheme of examination for that boiler under the Pressure Systems Safety Regulations 2000.
Every one of these is an operation. Insulation that has to be cut to do them will be cut, and that is why the six mountings on the machine we surveyed were found bare: 3.15 m², 9,095 W. Panelled with removable modules the same six shed 458 W and every operation above still happens the same way.
The fittings required on the pressure vessel for it to be operated: safety valve, main stop valve, feed check valve, water level gauge, pressure gauge, blowdown valve, fusible plug and manhole.
Mountings are required for safe operation and sit on the vessel. Accessories raise efficiency and sit in the circuit around it. A boiler runs without an economiser; it does not run without a safety valve.
An accessory. It sits in the feed line rather than on the vessel. The feed check valve on the shell is the mounting.
On the machine we surveyed six of them lose 9,095 W over 3.15 m² at 180 °C. Panelled the same six shed 458 W.
Yes, where the insulation is removable. Every module here comes off by hand: the stop valve keeps its travel, the safety valve keeps its lift, and the manhole keeps its swing.
The surveyed view this page came from, with every element on it.Open
→/ 02The accessory side of the same split, and the largest single loss on the machine at 18,327 W.Open
→/ 03The mounting measured on the other side of the boiler: 1,501 W across two flanges at 180 °C.Open
→| Survey | FLIR S62 Pro, emissivity 0.90, reflected 25 °C, 3 m, full radiometric correction. UK commercial boiler house. |
| Geometry | Rebuilt in CAD from the surveyed machine. Area allowances are stated on the page they are used on and are allowances, not measured areas. |
| Calculation | ISO 12241 steady state. Heat loss is calculated from the measured surface temperature and the modelled area — it is not metered. Full method, basis and limits. |
| Regulation | The Pressure Systems Safety Regulations 2000 · HSE L122, Safety of pressure systems · HSE INDG261, Pressure systems |
Where surface loss sits inside the indirect method, and what 49.8 kW is against the fuel input.Open
→/ 02What has to be opened, how often, and who signs it off under PSSR 2000.Open
→/ 03Which machine this is, and why the losing surfaces differ between the two.Open
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