Pipeline Safety Survey

Population Density Index (PDI) Survey

GPS-based PDI mapping for oil & gas pipelines across India — PNGRB-compliant location class determination and safety classification to meet regulatory requirements and protect communities.

PNGRB Compliant

ASME B31.8 Standard

OISD-GDN-226

GPS Geo-Tagged Reports

10,000+ km Pipeline Surveyed

25+ Major Clients

15+ States Covered

100% Regulatory Acceptance

HRP Infra engineers conducting GPS-based PDI survey for gas pipeline in Gujarat

IOCL & GAIL Trusted Partner

What Is PDI Survey?

Ensuring Pipeline Safety Through Population Mapping

The Population Density Index (PDI) Survey is a mandatory regulatory requirement for all natural gas and petroleum pipelines in India. It involves systematically counting and geo-tagging all buildings intended for human occupancy within a defined corridor along the pipeline, to classify the pipeline segment into Location Classes 1 through 4.

The location class directly governs critical pipeline design parameters — wall thickness, hydrostatic test pressure, valve spacing, and leak detection sensitivity. HRP Infra has completed PDI surveys for IOCL, Torrent Gas, Sabarmati Gas, GSPC, and multiple City Gas Distribution operators across India.

GPS Geo-Tagged Data: Every building is recorded with latitude/longitude, photo, and classification — fully auditable and GIS-ready.

PNGRB-Ready Reports: Deliverables are structured to meet PNGRB submission formats for pipeline licence and integrity management compliance.

Urban Expansion Tracking: We re-survey corridors to capture location class upgrades due to urbanisation near Ahmedabad, Surat, and major metros.

Regulatory Framework

Pipeline Location Classes Explained

As mandated by PNGRB and ASME B31.8, PDI determines the Location Class which drives all pipeline design and safety parameters.

Location Class	Building Count (per 1.6 km section)	Typical Area Type	Design Factor (Gas Pipeline)	Key Implications
Class 1	0 – 10 buildings	Rural / Wasteland / Offshore	0.72	Standard wall thickness; wider valve spacing permissible.
Class 2	11 – 45 buildings	Fringe areas, light industrial	0.60	Increased wall thickness; closer patrol intervals required.
Class 3	46+ buildings	Suburban housing, shopping areas	0.50	Higher hydrostatic test pressure; tighter valve spacing.
Class 4	Multi-storey 4+ floors	City centres, dense urban	0.40	Most stringent design; ILI inspection mandatory; enhanced leak detection.

Our PDI Services

Comprehensive PDI Survey Capabilities

From initial pipeline commissioning to periodic integrity updates — HRP Infra covers every phase of PDI compliance.

New Pipeline PDI Survey

End-to-end GPS-based building count and geo-tagging for new pipeline projects, producing location class maps and PNGRB-compliant PDI reports for licence applications.

PDI Update & Re-Survey

Periodic re-survey of existing pipeline corridors to identify class upgrades triggered by urbanisation, new housing colonies, or industrial development near Ahmedabad and other cities.

GIS-Based PDI Mapping

Full GIS integration of building data on pipeline alignment sheets, producing colour-coded location class maps in ArcGIS/QGIS for client GIS systems and regulatory submissions.

City Gas Distribution PDI

Specialised PDI surveys for City Gas Distribution (CGD) network corridors including steel and MDPE pipeline networks in Geographical Areas across Gujarat, Tamil Nadu, and Karnataka.

Cross-Country Pipeline PDI

High-volume PDI surveys for long-distance cross-country natural gas and petroleum pipelines (ONGC, IOCL, GAIL) spanning multiple states and diverse terrain types.

PDI Compliance Audit

Third-party review and audit of existing PDI data to verify accuracy, identify discrepancies, and update location class records as part of Pipeline Integrity Management Programme (IMP).

How We Do It

Our PDI Survey Methodology

A rigorous, GPS-driven process that ensures every building is accurately counted, geo-tagged, and classified — delivering audit-ready PDI data.

Corridor Definition

Establish the 220-metre (or specified) study corridor on each side of the pipeline centerline using GPS coordinates and pipeline as-built drawings.

Section Delineation

Divide the corridor into 1.6 km (1 mile) sections as per ASME B31.8 / PNGRB requirements for independent location class determination.

Field Building Count

GPS traversal of corridor to count, geo-tag, and photograph every building intended for human occupancy, logging address, building type, and floors.

GIS Data Processing

Import all geo-tagged data into GIS software to generate location class assignment maps overlaid on pipeline alignment sheets with colour coding.

PDI Report & Submission

Compile PNGRB-format PDI report with location class summary, GIS maps, photographic annex, and GPS data tables for regulatory submission and client records.

Why HRP Infra

Why Pipeline Operators Choose HRP Infra for PDI

With IOCL, Torrent Gas, and Sabarmati Gas in our client list, we understand the precision and compliance demands of pipeline PDI.

100% PNGRB Accepted Reports

All HRP Infra PDI reports have been accepted by PNGRB without data queries or rejection — our format and methodology are regulator-proven.

GIS-Integrated Deliverables

Location class maps are provided as GIS shapefiles and AutoCAD DWG, compatible with client pipeline management systems.

Rapid Field Mobilisation

With teams based in Ahmedabad and active in 15+ states, HRP Infra can mobilise PDI field teams within 5–7 days of work order.

Data Security & Confidentiality

Pipeline corridor data is handled under strict confidentiality agreements in line with security requirements of oil & gas infrastructure projects.

Long-Term PDI Partnership

We maintain client PDI records and provide scheduled re-surveys, enabling seamless location class updates for pipeline IMP compliance.

Expert Understanding of Standards

Deep working knowledge of PNGRB Regulations, ASME B31.8, OISD-GDN-226, and IS standards for natural gas pipeline design and safety.

Project Portfolio

PDI Survey Projects by HRP Infra

A selection of our delivered PDI survey projects for India's leading energy companies.

Indian Oil Corporation Limited

PDI Survey — Salaya–Rewari Pipeline (SRPL)

GPS-based PDI survey for the Right of Way corridor of SRPL spanning Tamil Nadu, Andhra Pradesh, and Karnataka — over 1,200 km covered.

GPS Mapping Multi-State PNGRB Report

Sabarmati Gas Limited

PDI for City Gas Network — Gandhinagar & Mehsana

Comprehensive PDI mapping for steel and MDPE pipeline network across Gandhinagar and Mehsana Geographical Areas — 50+ sq. km corridor surveyed.

CGD Network Gujarat GIS Deliverables

Torrent Gas Limited

Pipeline PDI — Moradabad Geographical Area

PDI survey for steel pipeline Right of Way in Moradabad GA, including building classification across rapidly urbanising peri-urban zones.

Steel Pipeline Urban Fringe Class 2 & 3

PDI Explained

Frequently Asked Questions

Everything you need to know about Population Density Index surveys for pipelines in India.

What is Population Density Index (PDI) in pipeline engineering?

Population Density Index (PDI) is a systematic count of buildings intended for human occupancy within a specified zone on either side of a pipeline. As per PNGRB and ASME B31.8 standards, this count determines the Location Class (1–4) of the pipeline corridor, which governs wall thickness, pressure testing, valve spacing, and other design requirements.

What are the 4 location classes for pipeline PDI?

Location Class 1 (0–10 buildings): Offshore or rural areas. Class 2 (11–45 buildings): Fringe areas of cities or industrial areas. Class 3 (46+ buildings): Suburban housing, shopping centres. Class 4 (multi-storey buildings above 4 floors): City centres and multi-storey complexes. Higher classes require more stringent pipeline design and safety measures.

Who mandates PDI surveys for pipelines in India?

The Petroleum and Natural Gas Regulatory Board (PNGRB) mandates PDI surveys for all natural gas and petroleum pipelines in India. PDI is also required under OISD-GDN-226 and ASME B31.8 standards. Non-compliance can result in pipeline licence rejection or suspension by PNGRB.

How is PDI survey conducted in the field?

PDI survey involves GPS/DGPS traversal of the pipeline corridor, counting all buildings intended for human occupancy within a 220-metre corridor on either side of the pipeline, at 1.6 km sections. Each building is geo-tagged, classified, and entered into GIS software to generate location class maps and a PNGRB-compliant PDI report.

How often should PDI surveys be updated?

PNGRB regulations recommend PDI surveys be updated whenever significant new construction is reported along the pipeline corridor, or as part of Integrity Management Programme (IMP) reviews — typically every 3–5 years. Rapid urbanisation near Ahmedabad, Surat, and metro cities often necessitates more frequent re-surveys.