The grades of 3 Chemicals stocks are better this week, according to the Portfolio Grader database. Every one of these stocks has an “A” (“strong buy”) or “B” overall (“buy”) rating.

This week, Airgas, Inc.’s (ARG) ratings are up from a C last week to a B. Airgas, Inc. is a distributor of industrial, medical, and specialty gases and hardgoods, such as welding equipment and supplies. The company also gets A’s in return on equity. For more information, get Portfolio Grader’s complete analysis of ARG stock.

Sinopec Shanghai Petrochemical Co. Ltd. Sponsored ADR Class H (SHI) gets a higher grade this week, advancing from a C last week to a B. Sinopec Shanghai Petrochemical Co. Ltd. Sponsored ADR Class H produces synthetic fibers, resins and plastic products. The company also gets A’s in free cash flow. For more information, get Portfolio Grader’s complete analysis of SHI stock.

Braskem S.A. Sponsored ADR Pfd Class A (BAK) boosts its rating from a C to a B this week. Braskem S.A. Sponsored ADR Pfd Class A produces and sells basic petrochemicals and thermoplastic resins in Brazil and internationally. The company also gets A’s in operating margin growth, earnings growth, earnings revisions, earnings surprise, earnings momentum, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of BAK stock.

Louis Navellier’s proprietary Portfolio Grader stock ranking system assesses roughly 5,000 companies every week based on a number of fundamental and quantitative measures. Stocks are given a letter grade based on their results — with A being “strong buy,” and F being “strong sell.” Explore the tool here.