India's experienced mounded bullet fabricator and contractor
An LPG mounded bullet is a horizontal cylindrical pressure vessel buried under an engineered earth mound. It eliminates fire-radiation distance requirements, removes the BLEVE risk associated with above-ground storage, and gives the bottling plant or refinery a safer, lower-footprint LPG inventory. But the engineering window is narrow: vessel design, foundation, sand bedding, mound geometry, cathodic protection and leak detection all have to work together. HAIL's leadership has executed 40+ mounded bullets across 7 major projects — under PESO certification with full SMPV(U) compliance.
Where space or capacity favours an above-ground sphere, we deliver Hortonsphere-style spherical pressure vessels — petal fabricated, post-weld heat treated, hydrotested and erected with our owned cranes.
What we deliver
Mounded LPG bullets
Horizontal cylindrical pressure vessels with dished ends, sand bedding, RCC saddles and engineered earth mound. Capacities 50 m× to 5,000 m×.
Spherical pressure vessels
Hortonsphere-style petal-fabricated spheres for LPG, propane, propylene and ammonia — supported on tubular columns or post-tensioned pedestal.
Petal fabrication
Hot/cold petal forming, sphere ring assembly, root and fill weld passes, full PWHT, 100% radiography.
Foundation & mound
RCC ringbeam, saddle pads, sand bedding to grading specification, plastic concrete cover, geogrid reinforcement and topsoil mound.
Cathodic protection & leak detection
Impressed current or sacrificial anode CP system; leak-detection tubes, fibre-optic temperature monitoring, level/pressure instrumentation.
Fire protection
Water spray system, deluge valves, foam pourer (where applicable), gas detection and shutdown logic.
Codes & statutory
- ASME Section VIII Div. 1 & 2 — pressure-vessel design and U-stamp.
- IS 2825 — Indian code for unfired pressure vessels.
- SMPV(U) Rules 2016 — Static and Mobile Pressure Vessels (Unfired).
- PESO / CCOE licensing for storage and handling of compressed gas.
- OISD-150 / OISD-144 — design and operating safety of LPG installations.
- EEMUA 190 — guidance on mounded LPG storage.
Reference experience
- 40+ PESO certified mounded bullets across 7 major projects for refineries and LPG bottling plants — leadership-led.
- LPG terminal scope — From design to PESO certification, hydrotest and commissioning.
- Petal fabrication of spheres for LPG and propylene service in chemical industries.
Materials & service
Carbon steel (SA 516 Gr. 70 / SA 537 Cl. 1), low-temperature carbon steel (SA 333 Gr. 6 for propane), stainless steel for ethylene/ammonia where applicable. Service: LPG, propane, butane, propylene, butadiene, ethylene, C2/C3, butane-1, ammonia, anhydrous HCl and hydrogen.
Why HAIL for LPG storage
- India experienced — 40+ mounded bullets, 7 major projects.
- Owned 200 / 100 / 50 / 20 MT crane fleet for sphere erection.
- 33,000 sq.ft. workshop at Kalol with PWHT and plate rolling capacity.
- Single-source for vessel + foundation + mound + CP + fire protection.
- RINA Consulting consortium for independent design assurance.
Mounded bullet vs LPG sphere — when to use which
The single biggest design decision for LPG storage is bullet vs sphere. Both store the same product, both are PESO-licensed, both are pressure vessels — but they suit different sites and different capacity requirements.
| Criterion | Mounded bullet | LPG sphere |
|---|---|---|
| Geometry | Horizontal cylindrical, buried under earth mound | Above-ground sphere on tubular columns |
| Capacity range | 200 — 5,000 m× each (typical) | 500 — 8,000 m× each (typical) |
| Fire-radiation distance | None — earth mound provides inherent fire protection | Required — needs water spray + spacing per OISD-118 |
| BLEVE risk | Eliminated by mound | Mitigated by water spray + structural fireproofing |
| Plot footprint | Larger (mound geometry) | Smaller (vertical structure) |
| CAPEX (per m×) | Lower for < 3,000 m× (no fireproofing/water spray) | Lower for > 5,000 m× (less plate per m× of volume) |
| Inspection access | Limited — manhole only after mound excavation | External inspection always accessible |
| Construction time | 20—30 weeks (plus 8 weeks earth mound) | 28—40 weeks (petal fabrication is long-lead) |
| Best for | Bottling plants, mid-size LPG terminals, refineries with plot constraint | Mega-terminals, propane & ethylene service, very large capacity |
HAIL designs and supplies both. We have delivered 40+ PESO-certified mounded bullets and several LPG sphere projects. The right choice depends on capacity, plot, fire-radiation distance to neighbours, soil bearing capacity, and CAPEX/OPEX trade-off.
Mounded bullet construction sequence
- Site survey, plot plan & FEED. Soil investigation, plot layout per OISD-118, fire-radiation distance verification, mound geometry calculation.
- Vessel design (ASME Section VIII + IS 2825). Shell + dished-end thickness for working pressure (typically 17—18 bar for LPG), saddle and lifting-lug design, nozzle schedule.
- PESO design approval. Drawings submitted to PESO for design vetting under SMPV(U) Rules 2016.
- RCC ringbeam & saddle pad construction. Reinforced concrete saddle pads with anchor bolts, sand bedding preparation, slope verification for drainage.
- Vessel fabrication. Workshop or site fabrication of shell courses, dished ends (cold or hot formed), longitudinal & circumferential welds, nozzle assemblies, manholes.
- NDE inspection. 100% RT on shell verticals, 100% RT on circumferential welds (per ASME), MT on attachments, hardness survey.
- PWHT. Local PWHT on critical welds; full PWHT for thicker shells or NACE service.
- Hydrotest at 1.3× MAWP. Vessel filled with water, held at test pressure for 30 minutes, leak inspection at all welds.
- External coating. Multi-layer coal-tar epoxy or fusion-bonded epoxy for buried-service corrosion protection. Holiday detection (sponge test or spark test).
- Cathodic protection installation. Impressed current or sacrificial anode CP system. Reference electrodes, leak-detection tubes, fibre-optic temperature monitoring.
- Vessel placement & mound construction. Vessel lowered onto saddle pads. Sand bedding to grading specification (selective fines, free of organics). Plastic concrete cover layer. Geogrid reinforcement. Topsoil mound to design profile. Vegetation/grassing for slope stability.
- Water spray, fire detection & integration. Surface water-spray system for cooling exposed nozzle areas. Fire and gas detection integration with plant ESD.
- PESO inspection & commissioning. Final PESO joint inspection, commissioning per approved procedure, CCOE licence issued.
LPG sphere construction sequence
- Site survey, plot plan & FEED. Plot layout per OISD-118, fire-radiation distance, foundation soil analysis.
- Sphere design. Diameter from capacity (sphere volume = 4/3 × × × r×), petal layout (typically 3 polar caps + crown plate + equatorial petals), shell thickness per ASME / IS 2825.
- RCC pedestal foundation. Reinforced concrete pedestal or piled foundation with anchor bolt cluster for support columns.
- Tubular support columns. Column fabrication (typically 8—12 columns), erection on foundation, bracing.
- Petal fabrication. Hot-pressed or cold-formed sphere petals from CS / LTCS plate (SA 516 / SA 537 Cl.1 / SA 333 Gr.6 for refrigerated). Each petal trimmed for sphere geometry.
- Petal assembly & sphere ring building. Assembly on jigs, ring-by-ring sphere build using crane lifts, alignment verification.
- Welding (most critical step). Triple-pass welding (root + fill + cap) on every sphere joint. ASME Section IX qualified WPS. Inter-pass temperature control. Welder rotation per qualification.
- NDE. 100% RT on every sphere weld. MT on attachments. Hardness survey post-PWHT. Ultrasonic check on heavier shell sections.
- PWHT. Full PWHT typically required — sphere wrapped in insulation with electric resistance heating elements; controlled ramp-up, hold, and ramp-down per ASME PWHT chart.
- Hydrotest. Sphere filled with water (significant load — pedestal must be designed for hydrotest weight), pressurised to 1.3× MAWP, held 30 minutes, leak inspection.
- External coating & insulation. Surface preparation to SA 2.5, multi-layer coating system. Refrigerated service: insulation + cladding (typically PUF + aluminium).
- Water spray fire protection. Surface water-spray ring with deluge valve, designed per NFPA 15 and OISD-118. Spray density typically 10.2 L/min/m×.
- PESO commissioning. Joint PESO inspection, commissioning, CCOE licence.
Materials & capacities — typical configurations
| Service | Material | Typical capacity | Working pressure |
|---|---|---|---|
| LPG (commercial mix) | SA 516 Gr.70 | 200 — 5,000 m× (bullet); 500 — 8,000 m× (sphere) | 17.5 bar |
| Propane (refrigerated) | SA 333 Gr.6 LTCS | 1,000 — 15,000 m× (sphere) | 1—4 bar |
| Butane | SA 516 Gr.70 | 500 — 8,000 m× | 5—8 bar |
| Propylene | SA 516 Gr.70 / SA 537 Cl.1 | 1,000 — 6,000 m× (sphere) | 20—25 bar |
| Ethylene (refrigerated) | SA 333 Gr.6 / 9% Ni for cryogenic | 1,000 — 10,000 m× | 1—4 bar |
| Butadiene | SA 516 Gr.70 (with inhibitor management) | 500 — 4,000 m× | 5—8 bar |
| Ammonia (anhydrous) | LTCS with NACE compliance | 500 — 15,000 m× | 17 bar atm; 1 bar refrigerated |
| Hydrogen | SA 516 with HTHA design per API 941 | 200 — 1,000 m× | 20—100 bar |
PESO licensing & statutory framework
Every LPG mounded bullet and sphere in India must operate under a PESO licence. The licensing process involves:
- Form-A application — submitted to PESO with site plan, plot plan, vessel drawings, P&ID, fire-water schematic, ERP.
- Site inspection by PESO officer — verifies plot layout, fire-radiation distances per OISD-118, fire-water capacity, ERP, training records.
- Approval of vessel design — ASME / IS 2825 calculations vetted; approved drawings stamped by PESO.
- Approval of fabricator — only PESO-empanelled fabricators can manufacture bullets & spheres. HAIL is empanelled.
- Pre-commissioning inspection — joint inspection of vessel, foundation, mound, water spray, instrumentation, ESD before first fill.
- CCOE licence issuance — after successful pre-commissioning, the Chief Controller of Explosives (CCOE) issues a 5-year operating licence.
HAIL's leadership has navigated this process 40+ times and maintains documented procedures for each PESO submission. We typically save clients 8—12 weeks in licensing through proactive engagement.
Reference projects — mounded bullets & spheres
- 40+ PESO-certified mounded bullets across 7 major LPG storage and refinery projects — leadership-led. Capacities 200—2,500 m×, lengths 30—80 m.
- LPG bottling plants for major Indian oil-marketing companies (IOCL, BPCL, HPCL).
- Refinery LPG storage for IOCL Barauni Coker-B Revamp (ongoing) — supports unit liquid product handling.
- Petal fabrication for spheres — propylene and propane storage for chemical industry.
Cost & timeline guide
- Mounded bullet 500 m×: —1.5—2.5 Cr (vessel + civil + mound), 18—24 weeks.
- Mounded bullet 1,500 m×: —3—6 Cr, 24—32 weeks.
- Mounded bullet 3,000 m×: —6—10 Cr, 28—36 weeks.
- LPG sphere 1,000 m×: —3—5 Cr, 24—32 weeks.
- LPG sphere 2,000 m×: —4—8 Cr, 28—40 weeks.
- LPG sphere 5,000 m×: —10—18 Cr, 36—48 weeks.
Pricing depends on metallurgy (LTCS adds 20—30%), service (refrigerated adds insulation cost), site logistics, and PESO licensing complexity. Prices include vessel, foundation, mound (for bullets), water spray, and PESO licensing support.
Frequently asked questions
Is HAIL PESO certified for mounded bullets?
Yes — our leadership has delivered 40+ PESO-certified mounded bullets across 7 major projects for refineries and LPG bottling plants. We are PESO-empanelled as a fabricator and handle full SMPV(U) Rules 2016 compliance, design vetting, site inspection and CCOE licence liaison.
Mounded bullet vs LPG sphere — which to choose?
Mounded bullets eliminate fire-radiation distance and BLEVE risk, use less specialised plot, and are typically lower CAPEX for capacities below 3,000 m×. Spheres are preferred for very large capacities (5,000+ m×) where they're more plate-efficient per m×, or where plot constraints favour vertical structure. See the comparison table above.
Which products can you store?
LPG (commercial), propane (refrigerated), butane, propylene, butadiene, ethylene (refrigerated cryogenic), C2/C3 mix, ammonia (anhydrous, atmospheric or refrigerated), anhydrous HCl, hydrogen, and other liquefied gases. Metallurgy is matched to the product, pressure, temperature and statutory requirement.
Do you do petal fabrication for spheres?
Yes — hot-pressed or cold-formed petals from CS / LTCS / SA 537 Cl.1. Full sphere assembly on jigs, ring-by-ring crane lifting, triple-pass welding (root + fill + cap) on every joint, full PWHT, 100% RT, and hydrotest at 1.3× MAWP.
Foundation, CP, fire system also?
Yes — turnkey scope: RCC ringbeam & saddle pads (mounded) or pedestal foundation (sphere), sand bedding to grading spec, plastic concrete cover, geogrid reinforcement, topsoil mound, vegetation. Full impressed-current or sacrificial-anode CP system. Leak detection tubes, fibre-optic temperature monitoring. NFPA 15 / OISD-118 compliant water spray with deluge valve.
What is the PESO licensing process and how long does it take?
Form-A application — PESO design vetting — site inspection by PESO officer — approval of fabricator (HAIL is empanelled) — pre-commissioning joint inspection — CCOE licence issuance. Total 12—20 weeks if proactively managed. We typically save clients 8—12 weeks through experienced submission and PESO liaison.
What pressure and temperature do mounded bullets and spheres handle?
Standard LPG (commercial mix): 17.5 bar working pressure, ambient temperature. Propane: 5—7 bar atm or refrigerated 1—4 bar. Propylene: 20—25 bar. Ethylene (refrigerated cryogenic): 1—4 bar at —104 ×C. Ammonia: 17 bar atmospheric or 1 bar refrigerated at —33 ×C. Hydrogen: up to 100 bar with HTHA design per API 941.
How does mound construction work?
After vessel placement on saddles: sand bedding to grading spec (selective fines, free of organics), plastic concrete cover for impact protection, geogrid reinforcement at intervals for slope stability, topsoil mound to design profile (typically 2:1 slope), vegetation/grassing for erosion control. Total mound height typically 1.2—1.5× vessel diameter.
What is BLEVE and how does mounding eliminate it?
BLEVE = Boiling Liquid Expanding Vapour Explosion — catastrophic failure of a pressurised LPG vessel exposed to fire, where the liquid flash-vaporises and ignites in a fireball. Mounding eliminates BLEVE because the earth mound thermally insulates the vessel from external fire, preventing the wall temperature rise that initiates BLEVE. This is why OISD-118 allows reduced fire-radiation distance for mounded bullets.
Cost guide for mounded bullets and spheres?
Mounded bullet 500 m×: —1.5—2.5 Cr, 18—24 weeks. 1,500 m×: —3—6 Cr, 24—32 weeks. 3,000 m×: —6—10 Cr. LPG sphere 1,000 m×: —3—5 Cr. 2,000 m×: —4—8 Cr. 5,000 m×: —10—18 Cr. LTCS for refrigerated service adds 20—30%.
Do you handle CCOE licensing and statutory liaison?
Yes — full liaison with PESO (Petroleum and Explosives Safety Organisation) and CCOE (Chief Controller of Explosives). Form-A submission, drawing approval, site inspection coordination, pre-commissioning joint inspection, licence issuance. 5-year licence renewals also handled.
What is the difference between LPG bullet and ammonia bullet?
LPG: ambient temperature service, SA 516 Gr.70 carbon steel, 17 bar working pressure. Ammonia: either ambient (similar to LPG) or refrigerated at —33 ×C requiring SA 333 Gr.6 LTCS metallurgy with NACE MR0175 compliance for stress corrosion cracking resistance. Different PESO licence categories.
Can you decommission an old LPG bullet or sphere?
Yes — controlled drain-down, vapour purging to flare, N— inerting, sectional cutting (cold cutting initially, hot work after gas-free certification), foundation handover. See our tank dismantling page.
How often must mounded bullets be inspected?
External CP system check: monthly. Cathodic protection annual survey. Full statutory inspection per PESO: every 5 years for licence renewal. We provide periodic inspection contracts and assist with statutory documentation.
Why hire HAIL for LPG storage?
India experienced — 40+ mounded bullets across 7 major projects, owned crane fleet (200/100/50/20 MT) for sphere erection, 33,000 sq.ft. workshop with PWHT capacity, single-point for vessel + foundation + mound + CP + fire protection + PESO licensing. RINA Consulting consortium for independent design assurance on mega-projects.