Hailestorm Consulting
PHAST Dispersion Analysis Request a study
DNV PHAST · Relief Systems · Fixed Price

Know where your relief plume goes — before the PHA asks.

Hailestorm Consulting runs PHAST dispersion analysis for pressure safety valves and vent stacks in refineries and chemical plants. You get defensible endpoint distances, clear plume plots, and a report that drops straight into your PHA, MOC, or relief-system file — at a fixed price quoted up front.

Request a study See fixed pricing

Launch offer: first 5 devices free on scopes of 10+ devices — see both offers

$5,000per PSV dispersion study
$10,000per vent stack study
PHASTindustry-standard DNV consequence modeling
Aerial view of a refinery with distillation towers, vent stacks, and relief headers
What the study answers

How far does the cloud travel to your toxic or flammable endpoint — and does it reach a building, a road, or the fence line?

Services & fixed pricing

Two studies. One price each. No hourly meter.

Relief dispersion work is usually buried in a large engineering contract. Here it is unbundled: a defined scope, a fixed fee, and a report written to stand on its own in an audit or revalidation.

Launch offers — two ways to get studies free

Limited launch period · Terms below
Launch offer 1

Your first 5 devices are free on a scope of 10+

Put 10 or more PSVs and/or vent stacks in a single scope and the first 5 devices are free — you only pay from the sixth device onward at the standard fixed rates. On an all-PSV scope that's a $25,000 saving; on vent stacks it can be worth up to $50,000.

Terms: Minimum 10 devices in one confirmed scope to qualify. The free devices are the first 5 devices in that scope; the mix (PSV vs. vent stack) and the exact saving are stated in your written scope confirmation before work starts. Launch offer — may end at any time for new inquiries.

Claim First 5 Free
Launch offer 2

Refer a client, get another 5 free

Know another plant that needs dispersion work? Refer a new client and when their inquiry turns into paid work, you earn 5 more PSVs/vents free — and there's no additional purchase required from you to redeem them.

Terms: The referred client must be a new client and their inquiry must convert to a paid engagement. Your 5 free devices are credited once that happens and can be used on a future scope with no minimum purchase. Tell us who referred you — or who you're referring — in the inquiry form so the credit is tracked.

Make or claim a referral

PSV Dispersion Study

For a single pressure safety valve relief scenario discharging to atmosphere or a vent header outlet.

$5,000per PSV
  • PHAST model of the governing relief scenario for one PSV
  • Distances to the toxic and/or flammable endpoints you specify
  • Plume / cloud footprint plots you can put in front of a PHA team
  • Written report: basis, inputs, assumptions, results, and conclusions
  • One round of comments incorporated
Start a PSV inquiry

Vent Stack Dispersion Study

For a vent stack or tailpipe system collecting one or more relief and vent sources.

$10,000per vent stack
  • PHAST modeling of the stack discharge, including the governing combined / single-source cases in scope
  • Endpoint distances compared against buildings, occupied areas, and the fence line
  • Stack-height sensitivity — what changes if the stack goes higher
  • Plume plots plus a written report with basis, inputs, and recommendations
  • One round of comments incorporated
Start a vent stack inquiry

Quick budget check

Count the devices in scope and see the total after the launch offer. With 10 or more devices, the first 5 are free — the estimator shows the before-offer total, the First 5 Free saving, and your net total. Mixed scopes are confirmed on inquiry — no surprises after the fact.

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Estimated fixed fee $5,000 1 PSV × $5,000

Prices are per device in scope and cover the study and report described above. If your scenario needs something outside that scope — multiple unrelated relief cases on one valve, a full relief-header study, or on-site work — you'll get a written quote before anything starts, not an invoice surprise.

What the study answers

The questions a dispersion study actually settles

01 How far does it go?

Downwind distances from the discharge point to the concentration endpoints that matter for your material — toxic endpoints and flammable (fraction of LFL) endpoints — under the weather cases in scope.

02 Who or what is inside it?

Whether the plume footprint reaches occupied buildings, control rooms, roads, unit boundaries, or the plant fence line — the finding that drives PHA recommendations and siting decisions.

03 Is the stack tall enough?

For vent stacks, how endpoint distances and ground-level concentrations change with discharge height and exit conditions, so a stack-height decision rests on modeling instead of rules of thumb.

04 Can we defend it?

A documented basis — relieving scenario, rate, composition, weather, and endpoints — modeled in DNV PHAST, the tool reviewers and auditors already recognize, with guidance consistent with API RP 521.

Common triggers for a study

PHA / revalidation finding MOC adding or moving a PSV New vent stack or stack raise Relief routed to atmosphere New building near a discharge Audit or insurer question Flare alternative evaluation Missing legacy documentation
How it works

From inquiry to report in four steps

No portal, no account, no kickoff bureaucracy. An email starts it, and the scope and fee are confirmed in writing before modeling begins.

STEP 1

Inquire

Send the form below or email directly. A few lines about the valve or stack and what question you're trying to answer is enough to start.

STEP 2

Confirm scope & data

You get a written confirmation of scope and the fixed fee, plus a short data checklist — PSV datasheet, relieving rate and composition, discharge location and height, and a plot plan.

STEP 3

PHAST modeling

The discharge is modeled in DNV PHAST across the agreed weather and endpoint cases. Gaps or oddities in the inputs get flagged to you, not silently assumed away.

STEP 4

Report & comments

You receive the report with plots and endpoint distances, ready for your PHA, MOC, or relief file. One round of comments is included in the fee.

Deliverables & inputs

What you receive — and what to send

Every study includes

  • Written report (PDF) — basis of design, scenario, inputs, and assumptions stated plainly.
  • Endpoint distance table — distance to each endpoint for each weather case modeled.
  • Plume plots — cloud footprint graphics suitable for PHA presentation.
  • Conclusions & recommendations — what the results mean for the discharge location, stack height, or occupancy in question.
  • One comment round — your reviewers' comments addressed in a revised issue.

Helpful to send with your inquiry

  • PSV datasheet or tag details — set pressure, size, and service.
  • Relieving scenario & rate — the governing case and required / rated capacity.
  • Fluid composition & conditions — what is relieved, at what temperature and pressure.
  • Discharge arrangement — direct atmospheric, tailpipe, or stack; height and location.
  • Plot plan — what's around the discharge: buildings, roads, fence line.

Don't have all of it? Send what you have — missing items become a short, specific list, not a stalled project.

FAQ

Questions, answered straight

What is a PHAST dispersion analysis?

PHAST is DNV's consequence-modeling software for process hazards. A dispersion analysis models how a released vapor cloud travels and dilutes downwind, and reports the distance at which concentration falls to a chosen endpoint — for example a toxic threshold or a fraction of the lower flammable limit (LFL).

For relief systems, it answers whether a PSV or vent stack discharge can reach people, buildings, or public areas at harmful or flammable concentrations.

Why does the price differ between a PSV and a vent stack?

A single PSV study covers one valve and its governing relief scenario. A vent stack usually collects several sources, so the work includes sorting out the governing discharge cases and evaluating stack height and combined effects — roughly twice the modeling and documentation effort, priced accordingly at $10,000 versus $5,000.

What endpoints do you model?

The endpoints in your facility's standards or PHA protocol — commonly toxic endpoints such as ERPG, AEGL, or IDLH-based values, and flammable endpoints expressed as a fraction of LFL. If you don't have a house standard, say so in the inquiry and the scope confirmation will propose endpoints for your approval before modeling starts.

Can the report be used in a PHA or audit?

Yes — that's what it's written for. The report states the scenario basis, inputs, assumptions, weather cases, and results with plume plots, so a PHA team, auditor, or reviewer can follow the work without needing the model files open in front of them.

What if I have several PSVs?

Use the budget estimator above: each additional PSV in scope is $5,000 and each vent stack is $10,000. Mention the full list in your inquiry — where valves share a discharge arrangement or scenario basis, the scope confirmation will say so plainly if that changes anything.

How does the "first 5 free" launch offer work?

Scope 10 or more devices — PSVs, vent stacks, or a mix — in a single confirmed engagement, and the first 5 devices are free. You pay only from the sixth device onward at the standard rates ($5,000 per PSV, $10,000 per vent stack).

Your written scope confirmation states exactly which devices are free and your total saving before any work starts, so there's no ambiguity at invoice time. It's a launch offer and may end for new inquiries at any time.

How does the referral reward work?

Refer a new client to Hailestorm Consulting. If their inquiry turns into paid work, you earn 5 free devices (PSVs or vent stacks) — no additional purchase is required from you to earn or redeem them.

To make sure the credit lands with the right person, the referred client should name you in their inquiry (there's a field for it on the form below), or you can email the referral to [email protected] ahead of time.

How do we start, and how is payment handled?

Send the inquiry form below or email [email protected]. You'll get a written scope and fixed-fee confirmation first; work starts once you accept it, and payment terms are set out in that confirmation. Nothing is billed on the inquiry itself.

Request a dispersion study

Tell us about the valve or stack. Submitting sends your inquiry directly by email to Hailestorm Consulting — you'll get an automatic email confirming it arrived, and a response within 48 hours.

Email inquiries to
[email protected]

Prefer to write your own email? Include the PSV tag or stack name, the material in service, and the question you're trying to answer — that's enough to scope it.

$5,000 per PSV  ·  $10,000 per vent stack

Don't miss the launch offers

First 5 free: scopes of 10+ devices get the first 5 free. Referral reward: refer a new client whose inquiry becomes paid work and earn another 5 free — no extra purchase needed. Pick the offer in the form so it's applied to your scope confirmation.

Submitting sends your inquiry by email to [email protected] — no email app is opened. FormSubmit may show a quick verification check before it sends; after it sends, an automatic confirmation email goes to your address and you are brought back here to a thank-you confirmation. If sending does not work, use the copy button below and email the inquiry yourself.