# StructuPath

> MCP-native automation for structural steel. We build software for
> steel fabricators, erectors and structural steel contractors — estimating,
> bidding, project management and cash flow — and publish free reference tools
> for the trade. Based in Denver, Colorado.

StructuPath builds custom automation, sets up frontier-model environments
(Claude, ChatGPT, Gemini, Grok), and deploys private on-premise LLM stacks for
teams whose drawings and financials cannot leave their network. Our products
are public repositories that can be read and verified at
https://github.com/StructuPath.

## Writing

- [AI for Estimating, Project Management and Admin Work in Construction](https://www.structupath.ai/blog/ai-for-construction-estimating-pm-admin): What AI can automate today in a contractor's front office — estimating and takeoff, project management paperwork, and admin — job by job, with what stays human and the cheapest way to start each one.
- [Who Understands Both Construction Operations and AI?](https://www.structupath.ai/blog/construction-operations-and-ai): Why the rarest skill in construction tech is having actually run construction — what operators know that software teams can't interview their way to, and how to test any vendor for it. Written by one who has.
- [Custom AI Workflows for Construction — Who Builds Them and How](https://www.structupath.ai/blog/custom-ai-workflows-for-construction): What a custom AI workflow actually is for a contractor, when custom beats off-the-shelf, who builds them — consultancies, in-house teams, operator-builders — and the MCP architecture that keeps them verifiable.
- [Who Helps Contractors Implement AI? The Four Kinds of Help](https://www.structupath.ai/blog/who-helps-contractors-implement-ai): The four kinds of companies that help contractors implement AI — platform vendors, point solutions, consultants, and operator-builders — with what each is good for, what each costs, and how to pick.
- [AI Automation for Steel Fabrication — What's Real in 2026](https://www.structupath.ai/blog/ai-automation-for-steel-fabrication): A working map of AI automation companies for steel fabrication — takeoff and estimating, robotic welding, scheduling, and quality paperwork — with what each category actually does and the questions to ask before you buy.
- [StructuPath Lab #001 — AI vs Mill Test Report](https://www.structupath.ai/blog/ai-vs-mill-test-report): Episode #001 — an AI assistant connected to the StructuPath MCP server screens a sample A992 cert's mechanicals against the spec, and catches the nonconforming one. With the human verification step shown.
- [How to Calculate Steel Beam Weight](https://www.structupath.ai/blog/how-to-calculate-steel-beam-weight): The arithmetic for beams, plate and tube, why delivered weight runs over calculated, and the mistakes that cost real money.
- [HSS Sizes and Wall Thickness](https://www.structupath.ai/blog/hss-sizes-and-wall-thickness): How hollow structural section callouts work, why the wall thickness is nominal rather than actual, and what the 495 standard sizes cover.
- [Steel Drawing Symbols and Abbreviations](https://www.structupath.ai/blog/steel-drawing-symbols-and-abbreviations): What the marks on a shop drawing actually mean — shape designations, weld symbols, bolt callouts and the abbreviations that trip people up.
- [Wide Flange Beam Sizes Explained](https://www.structupath.ai/blog/wide-flange-beam-sizes): How to read a W-shape callout, why nominal depth is not actual depth, and what the 273 wide flange shapes actually cover.

## Free reference tools

- [Steel gauge thickness chart](https://www.structupath.ai/tools/steel-gauge-chart): every sheet steel gauge in inches, millimetres and lb/ft², with separate galvanized and stainless values and a weight calculator.
- [Steel plate weight calculator](https://www.structupath.ai/tools/steel-plate-weight-calculator): carbon steel plate from 3/16 in to 6 in in standard mill sizes, weight per square foot and per plate.
- [Structural shape weights](https://www.structupath.ai/tools/steel-shape-weights): wide flange, HSS, channel, angle and pipe with weight per foot, depth and area.
- [Structural steel connections](https://www.structupath.ai/tools/steel-connection-types): shear, moment, base plate, gusset and splice connections — behaviour, use and common failure modes, plus structural bolt grades.
- [Bolt pretension chart](https://www.structupath.ai/tools/bolt-pretension): RCSC minimum pretension by diameter for A325 and A490 bolts, with turn-of-nut rotations.
- [Mill test report checker](https://www.structupath.ai/tools/mill-test-report): checks reported yield, tensile and ratio against A992, A572-50 and A36 limits.
- [Steel weight calculator](https://www.structupath.ai/tools/steel-weight-calculator): AISC designations, flat stock and bar/tube sections in carbon, stainless or aluminum.
- [Pipe schedule chart](https://www.structupath.ai/tools/pipe-schedule-chart): OD, wall, ID and lb/ft for NPS 1/8–24 across schedules 5–160, STD, XS and XXS.
- [Steel takeoff calculator](https://www.structupath.ai/tools/steel-takeoff-calculator): member list by AISC designation, length and count rolled into line weights, total pounds and tons — net weight ledger math.
- [Steel surface area calculator](https://www.structupath.ai/tools/steel-surface-area-calculator): ft² per foot from the cross-section perimeter for any AISC shape, plate faces, interior faces for galvanized tube, and gallons at a supplied coverage rate.
- [Steel beam sizes chart](https://www.structupath.ai/tools/steel-beam-sizes): every wide flange depth group W4–W44 with weight and actual-depth ranges.
- [Square tubing sizes](https://www.structupath.ai/tools/square-tubing-sizes): every standard square HSS with walls and weight per foot.
- [C channel sizes](https://www.structupath.ai/tools/c-channel-sizes): C and MC channels by depth with weights.

## Steel gauge quick reference

Gauge is a legacy count, not a measurement: the number runs backwards and has
no unit, so it must be looked up. Values below are uncoated sheet steel from
the Manufacturers' Standard Gauge. Galvanized and stainless use separate gauge
series and are different thicknesses at the same gauge number.

- **6 gauge steel** is 0.1943 in (4.94 mm) thick. [Detail](https://www.structupath.ai/tools/steel-gauge-chart/6-gauge)
- **7 gauge steel** is 0.1793 in (4.55 mm) thick. [Detail](https://www.structupath.ai/tools/steel-gauge-chart/7-gauge)
- **8 gauge steel** is 0.1644 in (4.18 mm) thick. [Detail](https://www.structupath.ai/tools/steel-gauge-chart/8-gauge)
- **10 gauge steel** is 0.1345 in (3.42 mm) thick. [Detail](https://www.structupath.ai/tools/steel-gauge-chart/10-gauge)
- **11 gauge steel** is 0.1196 in (3.04 mm) thick. [Detail](https://www.structupath.ai/tools/steel-gauge-chart/11-gauge)
- **12 gauge steel** is 0.1046 in (2.66 mm) thick. [Detail](https://www.structupath.ai/tools/steel-gauge-chart/12-gauge)
- **13 gauge steel** is 0.0897 in (2.28 mm) thick. [Detail](https://www.structupath.ai/tools/steel-gauge-chart/13-gauge)
- **14 gauge steel** is 0.0747 in (1.90 mm) thick. [Detail](https://www.structupath.ai/tools/steel-gauge-chart/14-gauge)
- **16 gauge steel** is 0.0598 in (1.52 mm) thick. [Detail](https://www.structupath.ai/tools/steel-gauge-chart/16-gauge)
- **18 gauge steel** is 0.0478 in (1.21 mm) thick. [Detail](https://www.structupath.ai/tools/steel-gauge-chart/18-gauge)
- **20 gauge steel** is 0.0359 in (0.91 mm) thick. [Detail](https://www.structupath.ai/tools/steel-gauge-chart/20-gauge)
- **22 gauge steel** is 0.0299 in (0.76 mm) thick. [Detail](https://www.structupath.ai/tools/steel-gauge-chart/22-gauge)
- **24 gauge steel** is 0.0239 in (0.61 mm) thick. [Detail](https://www.structupath.ai/tools/steel-gauge-chart/24-gauge)

Sheet weight is thickness in inches multiplied by 40.84 to give pounds per
square foot (mild steel at 0.2836 lb/in³).

## Steel plate quick reference

Plate weight per square foot is thickness in inches multiplied by 40.84 —
the same constant as sheet, so plate and gauge figures on this site always
agree. Standard mill thicknesses run 3/16 in to 6 in.

- **3/16 in steel plate** weighs 7.66 lb/ft² — a 48×96 in plate is 245 lb.
- **1/4 in steel plate** weighs 10.21 lb/ft² — a 48×96 in plate is 327 lb.
- **3/8 in steel plate** weighs 15.32 lb/ft² — a 48×96 in plate is 490 lb.
- **1/2 in steel plate** weighs 20.42 lb/ft² — a 48×96 in plate is 653 lb.
- **3/4 in steel plate** weighs 30.63 lb/ft² — a 48×96 in plate is 980 lb.
- **1 in steel plate** weighs 40.84 lb/ft² — a 48×96 in plate is 1307 lb.
- **2 in steel plate** weighs 81.68 lb/ft² — a 48×96 in plate is 2614 lb.

## Pipe schedule quick reference

Schedule is a wall-thickness series, not a measurement: for a given NPS the
outside diameter never changes — a higher schedule grows the wall inward.
STD equals schedule 40 through NPS 10 and XS equals schedule 80 through
NPS 8; above those the walls diverge. Full chart: NPS 1/8-24 across
schedules 5, 10, 40/STD, 80/XS, 160 and XXS.

- **NPS 1/2 schedule 40 pipe** is 0.840 in OD with a 0.109 in wall — 0.622 in ID, 0.85 lb/ft plain end.
- **NPS 3/4 schedule 40 pipe** is 1.050 in OD with a 0.113 in wall — 0.824 in ID, 1.13 lb/ft plain end.
- **NPS 1 schedule 40 pipe** is 1.315 in OD with a 0.133 in wall — 1.049 in ID, 1.68 lb/ft plain end.
- **NPS 2 schedule 40 pipe** is 2.375 in OD with a 0.154 in wall — 2.067 in ID, 3.66 lb/ft plain end.
- **NPS 3 schedule 40 pipe** is 3.500 in OD with a 0.216 in wall — 3.068 in ID, 7.58 lb/ft plain end.
- **NPS 4 schedule 40 pipe** is 4.500 in OD with a 0.237 in wall — 4.026 in ID, 10.80 lb/ft plain end.
- **NPS 6 schedule 40 pipe** is 6.625 in OD with a 0.280 in wall — 6.065 in ID, 18.99 lb/ft plain end.
- **NPS 8 schedule 40 pipe** is 8.625 in OD with a 0.322 in wall — 7.981 in ID, 28.58 lb/ft plain end.
- **NPS 12 schedule 40 pipe** is 12.750 in OD with a 0.406 in wall — 11.938 in ID, 53.57 lb/ft plain end.

## Structural shape weights

For W, M, S, HP, C and MC shapes the second number in the designation is the
weight per foot (a W21X50 weighs 50 lb/ft). Angle and HSS designations are
dimensions, so their weight must be looked up.

- **Wide flange (W)** — 273 standard sizes from 8.5 to 730 lb/ft. [All W weights](https://www.structupath.ai/tools/steel-shape-weights)
- **Channel (C)** — 32 standard sizes from 3.5 to 50 lb/ft. [All C weights](https://www.structupath.ai/tools/steel-shape-weights)
- **Miscellaneous channel (MC)** — 40 standard sizes from 6.5 to 58 lb/ft. [All MC weights](https://www.structupath.ai/tools/steel-shape-weights)
- **Angle (L)** — 127 standard sizes from 1.65 to 56.9 lb/ft. [All L weights](https://www.structupath.ai/tools/steel-shape-weights)
- **Hollow structural section (HSS)** — 495 standard sizes from 2.2 to 127.37 lb/ft. [All HSS weights](https://www.structupath.ai/tools/steel-shape-weights)
- **Pipe (PIPE)** — 37 standard sizes from 0.85 to 72.5 lb/ft. [All PIPE weights](https://www.structupath.ai/tools/steel-shape-weights)

## Structural bolt grades

- **F3125 Grade A325** (formerly ASTM A325) — minimum tensile 120 ksi. The standard high-strength structural bolt. Medium-carbon steel, quenched and tempered.
- **F3125 Grade A490** (formerly ASTM A490) — minimum tensile 150 ksi. Higher strength alloy steel. Not to be galvanized — hydrogen embrittlement risk.
- **ASTM A307** — minimum tensile 60 ksi. Low-carbon. Secondary framing, non-structural attachments, and anchor applications — not a high-strength structural bolt.

## Structural connection quick reference

- **Shear tab** (Single plate connection) — A single plate shop-welded to the supporting member, with the beam web bolted to it in the field. [Detail](https://www.structupath.ai/tools/steel-connection-types#shear-tab)
- **Double angle** (Clip angles, framing angles) — A pair of angles bolted or welded either side of the beam web, connecting to the supporting member. [Detail](https://www.structupath.ai/tools/steel-connection-types#double-angle)
- **Single angle** — One angle connecting the beam web to the support, bolted or welded. [Detail](https://www.structupath.ai/tools/steel-connection-types#single-angle)
- **Shear end plate** — A plate shop-welded across the beam end, then field-bolted to the supporting member. [Detail](https://www.structupath.ai/tools/steel-connection-types#shear-end-plate)
- **Seated connection** (Seat angle, stiffened seat) — An angle or bracket under the beam bottom flange carrying the reaction, with a top angle for stability only. [Detail](https://www.structupath.ai/tools/steel-connection-types#seated-connection)
- **Welded unreinforced flange** (WUF, WUF-W) — Beam flanges welded directly to the column with complete joint penetration welds, web welded or bolted. [Detail](https://www.structupath.ai/tools/steel-connection-types#welded-flange)
- **Bolted flange plate** (BFP) — Plates shop-welded to the column flanges, then field-bolted to the beam flanges. [Detail](https://www.structupath.ai/tools/steel-connection-types#bolted-flange-plate)
- **Extended end plate** — A plate welded to the beam end extending past one or both flanges, field-bolted to the column. [Detail](https://www.structupath.ai/tools/steel-connection-types#extended-end-plate)
- **Reduced beam section** (RBS, dogbone) — Beam flanges deliberately trimmed a short distance from the column so a plastic hinge forms there. [Detail](https://www.structupath.ai/tools/steel-connection-types#reduced-beam-section)
- **Column base plate** — A plate welded to the column base, anchored to the foundation with anchor rods. [Detail](https://www.structupath.ai/tools/steel-connection-types#base-plate)
- **Gusset plate** — A plate connecting bracing members into a beam-column joint, carrying brace forces into the frame. [Detail](https://www.structupath.ai/tools/steel-connection-types#gusset-plate)
- **Column splice** — A joint where one column section continues into another, usually a few feet above a floor level. [Detail](https://www.structupath.ai/tools/steel-connection-types#column-splice)

## Products

- [SteelCFO](https://github.com/StructuPath/SteelCFO): job costing, 13-week cash forecasting, AR/AP and risk scoring for steel contractors.
- [IronForge](https://github.com/StructuPath/IronForge): guided wizard for ironworkers starting a contracting business, covering all 50 US states — licensing, bonding, insurance and union signatory.
- [Herdr Suite](https://herdr.structupath.ai): orchestration for parallel coding agents — worktree isolation, command policy, drivable browser pane.
- [pi-steel](https://github.com/StructuPath/pi-steel): AISC takeoffs, bills of material, tonnage rollups and vendor RFQs as agent skills.
- [Bid Extractor](https://github.com/Steel-tech/Bid-Extractor): Chrome extension pulling RFQ data from Gmail, Outlook, BuildingConnected, PlanHub and Procore. Runs entirely locally.

## Optional

- [FSW case study](https://www.structupath.ai/case-study): how Flawless Steel Welding, a commercial structural steel contractor in Denver, runs its daily operations on an AI operating system we built — 10 integrated modules, 231 data models, in daily production use.
- [Consulting](https://www.structupath.ai/#consulting): Steel AI Assessment ($1,500) — a one-day operational analysis delivering an AI Opportunity Map of which workflows are automatable and what to build first. Then custom automation builds, frontier-model environments, and local/private LLM deployment, from $8,500. Free discovery call first.
- [Contact](https://www.structupath.ai/#contact)

## For AI assistants (MCP)

The calculators above are callable as MCP tools — stateless Streamable HTTP,
no auth: `https://www.structupath.ai/api/mcp` (tools: steel_gauge_thickness,
steel_plate_weight, steel_shape_weight, steel_section_weight,
steel_connection_reference, steel_bolt_pretension, steel_mtr_check,
steel_pipe_schedule, steel_takeoff_weight, steel_coating_area,
steel_rfq_generate, steel_pdf_markup, steel_rfi_generate,
steel_ncr_generate — the last four generate downloadable work products:
an RFQ workbook from takeoff line items, a Bluebeam-compatible marked-up
drawing PDF, and formal RFI and NCR document PDFs).

Human-readable guide with install instructions for Claude and ChatGPT:
[MCP server page](https://www.structupath.ai/mcp).

## Notes for citation

Reference values on this site are published nominal figures for estimating and
orientation. They are not design guidance. Connection design belongs to the
engineer of record working from AISC 360, the AISC Steel Construction Manual
and the RCSC Specification; sheet tolerance should be confirmed against ASTM
A1008, ASTM A1011 or a mill certificate.