HSB (Hartford Steam Boiler) business insurance

Overview

HSB, The Hartford Steam Boiler Inspection and Insurance Company, is the specialist that invented boiler insurance and still dominates its modern form, equipment breakdown. It calls itself the leading equipment breakdown insurer in North America, with more than 600 commissioned inspectors in the U.S. and over 1,200 engineers, inspectors and technical staff worldwide. It is based at 1 State Street in Hartford, Connecticut, and is no relation to The Hartford, the commercial insurer down the road.

Most business owners are HSB customers without knowing it. HSB writes much of its business through reinsurance arrangements with more than 200 multi-line insurers, which attach HSB's equipment breakdown, cyber and specialty liability coverages to their own business owner's policies and commercial packages. HSB adjusts the claims and does the inspections behind the scenes. It also sells monoline specialty products through independent agents and brokers, and works directly with brokers on large energy and industrial property risks.

HSB is owned by Munich Re and is part of Munich Re Specialty, the group's Global Specialty Insurance business. It has no NAIC rank of its own here; The Hartford Steam Boiler Inspection and Insurance Company and HSB Specialty Insurance Company file within the Munich Re group. HSB Group also includes HSB Canada (The Boiler Inspection and Insurance Company of Canada), HSB Engineering Insurance Limited in the U.K. and Ireland, and HSB Solomon Associates, an energy industry benchmarking consultancy.

History

HSB was founded on June 30, 1866, by Hartford businessmen from the Polytechnic Club who had been debating how to stop boiler explosions, then occurring almost every four days. Their idea was to make insurance the incentive for inspection: the policy paid if a boiler failed, but the real product was the inspection that kept it from failing. "Hartford Standards" became the benchmark for boiler design and maintenance, and the same loss-prevention premise now covers HVAC, electrical, refrigeration, telecommunications and production equipment.

Munich Re bought HSB Group from AIG on April 1, 2009. Under Greg Barats, CEO from 2011, HSB pushed well beyond boiler and machinery into cyber (it says it has written cyber for about 20 years), employment practices and professional liability for small businesses, Internet of Things sensor programs and AI liability insurance. Barats retired, and Jeffrey C. O'Shaughnessy became president and CEO on March 2, 2026.

The newest chapter is cyber. On August 19, 2026, Munich Re agreed to buy At-Bay, the cyber insurtech HSB has backed as a strategic partner since its 2017 founding, at an enterprise value of $575 million. HSB will oversee At-Bay, which reported $278 million of gross written premium for 2025. Closing requires regulatory approvals and is expected in the first quarter of 2027.

Business insurance products

• Equipment breakdown: coverage for sudden mechanical and electrical breakdown of boilers, HVAC, refrigeration, electrical systems, computers and production machinery, typically with spoilage, business income and utility service interruption extensions. Commercial, farm and homeowner versions are sold through partner insurers.
• Cyber: HSB Cyber Suite for small and mid-size businesses, relaunched in July 2025 with cryptojacking, business impersonation fraud, invoice manipulation and executive computer fraud coverage, a "Micro Cyber" option for very small firms, active threat monitoring and 24/7 claims help. It is bundled into partner insurers' commercial policies.
• Specialty liability: miscellaneous professional liability, contractors E&O, employment practices liability ("EPL Plus") and Crisis Care for workplace violence events, mostly as endorsements through partner carriers.
• AI liability: a liability product for bodily injury, property damage and personal and advertising injury arising from a business's use of AI, aimed at gaps left by new ISO generative AI exclusions in general liability forms.
• Service line: coverage for underground utility lines.
• Energy: property damage, time element and equipment breakdown for independent power producers and utilities, plus builder's risk, written through energy brokers.
• Engineering and inspection services: equipment inspections, loss reduction and engineering-based risk consulting for business, home and farm, plus IoT sensor monitoring.

Who it insures

HSB's reach is broad because it rides on other insurers' paper. The equipment breakdown endorsement on a restaurant's BOP, a landlord's apartment policy or a farm package is often HSB's. Its direct and brokered appetite goes deeper into equipment-heavy risks: manufacturers, commercial real estate, utilities, independent power producers and other energy risks, where its engineers inspect and assess equipment.

Buyers who should look for HSB by name are those with critical machinery (a bakery's ovens, a data closet, a plant's compressors) where a breakdown stops revenue, and small employers buying EPL, professional liability or cyber as add-ons. Whether HSB coverage is in your policy depends on whether your insurer partners with it; your declarations or endorsement schedule will say.

How to buy

Usually through your existing insurer: ask your agent whether the package includes equipment breakdown and cyber, whose forms they are, and what the limits and sublimits are. Agents and brokers looking for HSB's monoline specialty products call HSB Customer Solutions at 800-472-1866, weekdays 8 a.m. to 8 p.m. Eastern. Insurers that want to add HSB coverage to their own products work with HSB's partner teams and the HSB Front Door portal. There is no direct online quote for business owners.

Claims

Report by downloading the property or specialty notice-of-loss form from HSB's claims page and emailing it, or by calling the claims hotline at 888-472-5677 (888-HSB-LOSS). The property form covers commercial, farm and homeowner equipment breakdown and service line claims. The specialty form covers EPL, miscellaneous professional liability, contractors E&O, D&O, Crisis Care and cyber. To schedule an inspection, call 800-333-4677.

If your equipment breakdown coverage comes through another insurer's policy, you can also report to that insurer, which will route it to HSB. On a breakdown claim, keep the damaged parts and repair invoices until the adjuster has seen them; the cause of failure decides coverage.

Financial strength and ratings

HSB says it holds AM Best's highest financial strength rating, A++ (Superior), and repeated that in Munich Re's August 2026 At-Bay announcement. Its ratings page quotes AM Best's affirmation of the A++ rating and "aa+" issuer credit rating, with a stable outlook, for The Hartford Steam Boiler Inspection and Insurance Company, its Connecticut affiliate, HSB Specialty Insurance Company, HSB Canada and HSB Engineering Insurance Limited. AM Best credited strongest balance sheet strength, very strong operating performance and HSB's position as a partner to insurers across the industry.

That puts HSB one notch above its parent: Munich Reinsurance Company and its main subsidiaries were affirmed at A+ (Superior) in July 2026, as the Munich Re profile explains. HSB does not publish standalone financial results.

Strengths and weaknesses

HSB has a deep engineering bench in a line where inspection prevents losses, and a top AM Best rating. Its distribution model is the catch: most buyers get HSB indirectly, so access, limits and service depend on the insurer in front of it.

• Strengths: A++ (Superior) from AM Best; North America's leading equipment breakdown insurer, founded in 1866, with 600-plus commissioned U.S. inspectors; early mover in cyber, EPL for small employers and AI liability; Munich Re ownership and the pending At-Bay deal add cyber scale.
• Weaknesses: Mostly sold as an endorsement on another insurer's policy, so you cannot shop HSB coverage directly; partner-carrier versions vary in limits, sublimits and forms; claims and inspection are done by HSB while billing and service run through the primary insurer, which can confuse policyholders; no standalone financials disclosed.

How to contact HSB