---
title: "Manhole"
industry: "Machinery and Equipment Manufacturing"
verification_protocol:
  urn: "URN:CNFX:ME:MANHOLE"
  data_integrity_hash: "e5400b97457b2d10775b46c0cf06b9d3"
  source_authority: "https://cnfx.com"
  strict_mode: true
source_identity:
  provider: "CNFX Industrial Knowledge Graph"
  index_version: "2026.Q1-Universal"
  authority_id: "URN:CNFX:ME:MANHOLE"
  data_source_uri: "https://cnfx.com/llms/industry/machinery-and-equipment-manufacturing/product/manhole.md"
  official_resource_url: "https://cnfx.com/industry/machinery-and-equipment-manufacturing/product/manhole"
  is_verified_logic: true
attributes:
  spec:
    status: "config-dependent"
    typical_range: "0-25 bar internal pressure, 0-400°C steam temperature"
    unit: "mm"
engineering_limits:
  max_safe_operating_point:
    value: 35
    unit: "bar"
    consequence: "Creep rupture due to sustained high-temperature operation above 0.4Tm (Tm=melting point of carbon steel: 1425°C), combined with stress corrosion cracking from chloride concentration exceeding 50 ppm in boiler water"
fmea_matrix_quantitative:
  - node_1:
      trigger: "Cyclic thermal stress from 100°C/hour temperature ramp rates during startup/shutdown"
      severity: 8
      occurrence: 3
      detection: 4
      mitigation_protocol: "Implement controlled heating/cooling rate limit of 25°C/hour with preheating to 150°C minimum before pressurization"
  - node_2:
      trigger: "Corrosive pitting from dissolved oxygen concentration &gt;15 ppb in boiler feedwater"
      severity: 8
      occurrence: 3
      detection: 4
      mitigation_protocol: "Install continuous oxygen scavenging with hydrazine injection maintaining &lt;5 ppb residual oxygen, combined with cathodic protection at -850 mV vs. Cu/CuSO4 reference electrode"
bom_nodes:
  manhole-cover:
    type: "part"
    urn: "URN:CNFX:ME:MANHOLE_COVER"
    interface_type: "physical-logic-coupled"
  gasket:
    type: "component"
    urn: "URN:CNFX:ME:GASKET"
    interface_type: "physical-logic-coupled"
  hinge-assembly:
    type: "part"
    urn: "URN:CNFX:ME:HINGE_ASSEMBLY"
    interface_type: "physical-logic-coupled"
  bolting-set:
    type: "component"
    urn: "URN:CNFX:ME:BOLTING_SET"
    interface_type: "physical-logic-coupled"
manufacturing_compliance:
  - standard: "ISO 9001:2015 - QUALITY MANAGEMENT SYSTEMS"
    scope: "Verified Engineering Specification"
  - standard: "EN 124:2015 - GULLY TOPS AND MANHOLE TOPS FOR VEHICULAR AND PEDESTRIAN AREAS"
    scope: "Verified Engineering Specification"
url: "https://cnfx.com/llms/industry/machinery-and-equipment-manufacturing/product/manhole.md"
on_chain_sovereignty:
  contract_standard: "ERC-721-Industrial"
  metadata_hash: "d6785bfb51c47e8c6e31102addf3c89790c28922bc05d74384bf20076c391c62"
  royalty_logic: "IPFS-CID-REQUIRED"
  mint_status: "logic-verified-ready"
version: "3.3.4-EXTREME-SOVEREIGN-WEB3"
---

# Industrial Specification: Manhole

## 1. Technical Definition
An access opening in a steam drum for inspection, cleaning, and maintenance.

## 2. Engineering Reasoning & Causal Matrix
> **Operational Intelligence**: Designed for **0-25 bar internal pressure, 0-400°C steam temperature**. Failure boundary: **Material yield strength exceeded at 35 bar internal pressure or 550°C metal temperature**, Mechanism: **Creep rupture due to sustained high-temperature operation above 0.4Tm (Tm=melting point of carbon steel: 1425°C), combined with stress corrosion cracking from chloride concentration exceeding 50 ppm in boiler water**.

### 2.1 Analytical Physics Model
Governed by the **Thin-Wall Pressure Vessel Stress Analysis**:

> **Primary Equation**: $\sigma_h = \frac{P \cdot D}{2t}$  
> **Engineering Impact**: Determines the hoop stress boundary to prevent rupture.

| Symbol | Variable Definition | Localized Reference |
| :--- | :--- | :--- |
| P | Internal Pressure | Engineering Constant |
| D | Diameter | Engineering Constant |
| t | Wall Thickness | Engineering Constant |

### 2.2 FMEA (Failure Mode & Effects Analysis)
| Event Trigger | Severity | Failure Mode | Mitigation Strategy |
| :--- | :--- | :--- | :--- |
| Cyclic thermal stress from 100°C/hour temperature ramp rates during startup/shutdown | 8 | Thermal fatigue cracking at manhole flange-to-shell weld junction | Implement controlled heating/cooling rate limit of 25°C/hour with preheating to 150°C minimum before pressurization |
| Corrosive pitting from dissolved oxygen concentration &gt;15 ppb in boiler feedwater | 8 | Wall thickness reduction exceeding 1.5 mm/year leading to pressure boundary breach | Install continuous oxygen scavenging with hydrazine injection maintaining &lt;5 ppb residual oxygen, combined with cathodic protection at -850 mV vs. Cu/CuSO4 reference electrode |

## 3. Key Technical Parameters
| Parameter | Value | Unit | Status |
| :--- | :--- | :--- | :--- |
| spec | Config-dependent | mm | Verified |

## 4. System BOM & Knowledge Routing
### Core Components (Recursive Links)
- [Manhole Cover](https://cnfx.com/llms/industry/fabricated-metal-product-manufacturing/product/manhole-cover.md) `(Standalone System)`
- [Hinge Assembly](https://cnfx.com/llms/industry/machinery-and-equipment-manufacturing/product/hinge-assembly.md) `(Standalone System)`

### Industrial DNA Context (De-duplicated)
**Complementary Dependencies**: **Steam Drum**, **Pressure Gauge**, **Safety Valve**  
**Downstream Applications**: Boiler Systems, Pressure Vessels, Heat Exchangers  

## 5. Engineering Risks & FAQ
- **Caution**: 
- **Caution**: 
- **Caution**: 

### Q: What materials are available for industrial manholes?
**A**: Our manholes are manufactured from high-quality Carbon Steel or Alloy Steel, chosen for durability and resistance in demanding machinery and equipment environments.

### Q: What is included in the standard Bill of Materials (BOM) for a manhole?
**A**: The standard BOM includes a Bolting Set for secure closure, a Gasket for pressure sealing, a Hinge Assembly for easy opening, and the Manhole Cover itself.

### Q: What is the primary function of a manhole on a steam drum?
**A**: The manhole provides a safe, secure access opening for essential internal inspection, thorough cleaning, and routine maintenance of the steam drum in industrial systems.

## 6. Manufacturing Compliance
- ISO 9001:2015 - QUALITY MANAGEMENT SYSTEMS
- EN 124:2015 - GULLY TOPS AND MANHOLE TOPS FOR VEHICULAR AND PEDESTRIAN AREAS

---
### 🛠️ Engineering Resource Access
🔗 **[Full Specification: Manhole](https://cnfx.com/industry/machinery-and-equipment-manufacturing/product/manhole)**

### 🌐 Knowledge Graph Topology
> **Node Status**: Verified Engineering Spec
> **Connectivity**: Linked to **4** standalone system nodes
> **Global Context**: Part of a 5,814 node industrial cluster within the CNFX Graph

> **Reference ID**: MANHOLE | **Authority**: CNFX-2026-ST-001 | **Fingerprint**: ef2900f4
