What Preparations Should Be Made for Boiler Shutdown

Step-by-step boiler shutdown checklist for safe short- and long-term layups. Covers cooldown, blowdown, wet vs. dry layup, LOTO, corrosion protection and restart tips.

Quick checklist (at-a-glance)

1. Reduce load, follow manufacturer cooldown steps.
2. Perform controlled blowdown and drain when safe.
3. Choose wet or dry layup and apply chemical treatment if required.
4. Isolate fuel, steam, feedwater and apply LOTO.
5. Clean, inspect, and protect fireside and waterside.
6. Document steps, tag equipment, and prepare a restart plan.

1) Plan, schedule and communicate

• Create a written shutdown plan that lists responsible people, step order, required permits, and safety precautions. Notify operations, maintenance, and safety teams in advance. Good planning prevents accidental energization or unsafe work.

2) Cool down safely and reduce load

• Reduce firing rate and lower load gradually per the manufacturer’s instructions. Avoid rapid cooling that can crack refractory or cause thermal stress. Confirm pressure = 0 and water temperature is below the safe opening limit (often <140°F/60°C) before opening equipment.

3) Controlled blowdown and draining

• Carry out bottom and surface blowdowns to remove sludge and sediments before draining. Blowdown frequency should increase in the days leading up to shutdown to reduce hard deposits. Only drain after pressure/temperature are safe and venting is established.

4) Decide: wet layup vs dry layup (and chemical protection)

• Short-term (days–weeks): Wet layup — keep the boiler full of chemically treated water (target pH and inhibitor levels per your chemical supplier). This prevents oxygen attack and localized corrosion.
• Long-term (months+): Dry layup — drain thoroughly, dry the interior, and use desiccants or inert gas (nitrogen) to keep moisture out; protect exposed metal with corrosion inhibitors or coatings. The National Board recommends moisture absorbers (silica gel, lime) for dry storage.

5) Isolate energy sources and apply Lockout-Tagout (LOTO)

• Physically isolate and lockout/tagout fuel (gas/oil), electrical power, feedwater, steam outlet, blowdown lines, chemical feeds and any auxiliary steam services. Consider double block-and-bleed or blind flanges where safety demands it — don’t rely solely on check valves. Document who holds each lock.

6) Clean and inspect fireside and waterside

• Clean soot and scale from the fireside while the boiler is still warm (easier removal). Open manways and inspect tubes, brickwork, gaskets, and refractory. Use drying fans or heaters for dry layup; inspect and repair any damaged insulation, seals or valves.

7) Protect piping, valves and ancillary equipment

• Drain and isolate connected piping that can trap water and freeze. Protect pumps, seals, and condensate tanks per vendor instructions. Label isolated valves and blank flanges as needed.

8) Documentation, tagging and restart plan

• Keep a shutdown log (who did what and when), tag all locked valves/switches, and record chemical concentrations and inhibitor additions. Prepare a step-by-step restart checklist and pre-order any replacement parts discovered during inspection.

Common questions (short)

• How long is a “short” layup? Typically up to ~10 days; semi-short up to 30 days. For these periods wet layup is common. For long-term (months) prefer dry layup.
• Should I add chemicals before or after shutdown? For wet layup, treat and adjust water chemistry to the target levels before isolating the boiler. Follow your water-treatment vendor’s instructions.