{"id":428,"date":"2026-09-17T13:32:21","date_gmt":"2026-09-17T13:32:21","guid":{"rendered":"https:\/\/yash-impex.com\/blog\/?p=428"},"modified":"2026-09-21T18:40:21","modified_gmt":"2026-09-21T18:40:21","slug":"astm-a335-grade-p1-p2-p9-alloy-steel-pipes","status":"publish","type":"post","link":"https:\/\/yash-impex.com\/blog\/astm-a335-grade-p1-p2-p9-alloy-steel-pipes\/","title":{"rendered":"ASTM A335 Grade P1, P2 & P9 Alloy Steel Pipes"},"content":{"rendered":"\n

Power plants, refineries and petrochemical complexes run at temperatures where ordinary carbon steel loses strength or oxidises quickly. For these conditions, engineers specify ASTM A335<\/strong> ferritic alloy steel pipe. This guide compares three commonly ordered grades, P1, P2 and P9, and explains how to choose between them.<\/p>\n\n\n\n

What Is ASTM A335?<\/h4>\n\n\n\n

ASTM A335 (ASME SA335) covers seamless ferritic alloy-steel pipe for high-temperature service. The alloying elements, mainly chromium and molybdenum, improve creep strength, oxidation resistance and performance under sustained heat. Pipes are supplied in sizes from small bore up to large-diameter headers and are normally normalised and tempered or annealed, depending on the grade.<\/p>\n\n\n\n

ASTM A335 P1 Pipes (Carbon-Molybdenum Steel)<\/h4>\n\n\n\n

ASTM A335 P1 pipes<\/strong> are a carbon-molybdenum grade containing roughly 0.44\u20130.65% molybdenum. The molybdenum adds strength at elevated temperature compared with plain carbon steel. P1 has a minimum tensile strength of 55 ksi (380 MPa) and a minimum yield strength of 30 ksi (205 MPa). It is a good fit for moderate-temperature steam lines, boiler auxiliaries and general refinery piping where high corrosion or oxidation resistance is not needed.<\/p>\n\n\n\n

P1 is weldable, but preheating and, in many cases, post-weld heat treatment are recommended. Designers should also check the design code for long-term limits on carbon-molybdenum steels at higher temperatures. See our ASTM A335 Grade P1 Alloy Steel Pipes<\/a> page for available sizes.<\/p>\n\n\n\n

ASTM A335 P2 Pipes (Chrome-Moly Steel)<\/h4>\n\n\n\n

ASTM A335 P2 pipes<\/strong> contain about 0.5% chromium and 0.5% molybdenum. The added chromium gives better oxidation resistance and creep behaviour than P1. Minimum tensile and yield strengths are the same as P1 (55 ksi and 30 ksi), but P2 gives more headroom in service where temperatures run higher. Typical uses include boiler tubing systems, superheater and reheater connections, and process piping in power and refining plants.<\/p>\n\n\n\n

Details are on our ASTM A335 Grade P2 Alloy Steel Pipes<\/a> page.<\/p>\n\n\n\n

ASTM A335 P9 Pipes (9% Chrome, 1% Moly)<\/h4>\n\n\n\n

ASTM A335 P9 pipes<\/strong> are a high-chromium grade with 8\u201310% chromium and roughly 1% molybdenum. The chromium content gives strong resistance to oxidation, scaling and sulphidation, which makes alloy steel P9 pipes<\/strong> valuable in the harshest heat-processing environments. Minimum tensile strength is 60 ksi (415 MPa) and minimum yield strength is 30 ksi (205 MPa).<\/p>\n\n\n\n

Because P9 is an air-hardening steel, welding needs careful control: correct preheat, controlled interpass temperature and post-weld heat treatment. Buyers should require qualified welding procedures for fabrication. P9 typically goes into refinery heater tubes, superheaters, high-temperature steam lines and petrochemical crackers. See ASTM A335 Grade P9 Alloy Steel Pipes<\/a>.<\/p>\n\n\n\n

Quick Comparison<\/h4>\n\n\n\n
Feature<\/th>P1<\/th>P2<\/th>P9<\/th><\/tr><\/thead>
Alloy type<\/td>C-0.5Mo<\/td>0.5Cr-0.5Mo<\/td>9Cr-1Mo<\/td><\/tr>
Tensile (min)<\/td>55 ksi<\/td>55 ksi<\/td>60 ksi<\/td><\/tr>
Yield (min)<\/td>30 ksi<\/td>30 ksi<\/td>30 ksi<\/td><\/tr>
Oxidation resistance<\/td>Basic<\/td>Moderate<\/td>High<\/td><\/tr>
Typical service<\/td>Moderate-temp steam<\/td>Higher-temp steam, boilers<\/td>Refinery heaters, superheaters<\/td><\/tr>
Relative cost<\/td>Lowest<\/td>Medium<\/td>Highest<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

How to Select the Right Grade<\/h4>\n\n\n\n

Selection should follow design temperature, pressure, corrosive medium and applicable code (ASME B31.1 for power piping, B31.3 for process piping). As a rule, P1 suits moderate temperatures and budgets, P2 suits mid-range high-temperature duties, and P9 is chosen when oxidation, sulphidation or very high temperatures rule out lower alloys. Choosing a higher grade than needed raises project cost, and choosing a lower one risks premature failure and shutdowns.<\/p>\n\n\n\n

Quality Checks Buyers Should Insist On<\/h4>\n\n\n\n
    \n
  • Chemical and mechanical test reports (MTC EN 10204 3.1 or 3.2)<\/li>\n\n\n\n
  • Hydrostatic or NDE testing on every pipe<\/li>\n\n\n\n
  • Flattening and bend tests as required by the specification<\/li>\n\n\n\n
  • Heat treatment records (normalising and tempering or annealing)<\/li>\n\n\n\n
  • PMI verification, since alloy grades can be mixed up visually<\/li>\n\n\n\n
  • Third-party inspection before dispatch for critical projects<\/li>\n<\/ul>\n\n\n\n

    Sourcing A335 Alloy Steel Pipes from Yash Impex<\/h4>\n\n\n\n

    Yash Impex is an ISO 9001:2015 certified, Government of India recognised Export House based in Mumbai. We supply ASTM A335 P1, P2 and P9 pipes<\/strong>, along with P5, P11 and P22, to refineries, power utilities, EPC contractors and industrial distributors across Africa, the Middle East and Asia. Our strength is reliable sourcing, complete documentation, export-standard packing and prices that suit bulk buyers.<\/p>\n","protected":false},"excerpt":{"rendered":"

    Power plants, refineries and petrochemical complexes run at temperatures where ordinary carbon steel loses strength or oxidises quickly. For these […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"page_builder":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-428","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t